diff --git a/Library/Homebrew/.rubocop.yml b/Library/Homebrew/.rubocop.yml
index 772dce1f46..ba94d7d67d 100644
--- a/Library/Homebrew/.rubocop.yml
+++ b/Library/Homebrew/.rubocop.yml
@@ -16,7 +16,7 @@ Lint/NestedMethodDefinition:
 Metrics/AbcSize:
   Max: 280
 Metrics/BlockLength:
-  Max: 100
+  Max: 102
   Exclude:
     # TODO: extract more of the bottling logic
     - "dev-cmd/bottle.rb"
diff --git a/Library/Homebrew/brew.rb b/Library/Homebrew/brew.rb
index a5fae3c604..945c14dea1 100644
--- a/Library/Homebrew/brew.rb
+++ b/Library/Homebrew/brew.rb
@@ -179,10 +179,13 @@ rescue MethodDeprecatedError => e
   exit 1
 rescue Exception => e # rubocop:disable Lint/RescueException
   onoe e
-  if internal_cmd && defined?(OS::ISSUES_URL) &&
-     !Homebrew::EnvConfig.no_auto_update?
-    $stderr.puts "#{Tty.bold}Please report this issue:#{Tty.reset}"
-    $stderr.puts "  #{Formatter.url(OS::ISSUES_URL)}"
+  if internal_cmd && defined?(OS::ISSUES_URL)
+    if Homebrew::EnvConfig.no_auto_update?
+      $stderr.puts "#{Tty.bold}Do not report this issue until you've run `brew update` and tried again.#{Tty.reset}"
+    else
+      $stderr.puts "#{Tty.bold}Please report this issue:#{Tty.reset}"
+      $stderr.puts "  #{Formatter.url(OS::ISSUES_URL)}"
+    end
   end
   $stderr.puts e.backtrace
   exit 1
diff --git a/Library/Homebrew/cleanup.rb b/Library/Homebrew/cleanup.rb
index cf5952e385..eec28b3fe8 100644
--- a/Library/Homebrew/cleanup.rb
+++ b/Library/Homebrew/cleanup.rb
@@ -161,6 +161,7 @@ module Homebrew
       if cleanup.periodic_clean_due?
         cleanup.periodic_clean!
       elsif f.latest_version_installed? && !cleanup.skip_clean_formula?(f)
+        ohai "Running `brew cleanup #{f}`..."
         cleanup.cleanup_formula(f)
       end
     end
@@ -191,8 +192,11 @@ module Homebrew
         ohai "Would run `brew cleanup` which has not been run in the last #{CLEANUP_DEFAULT_DAYS} days"
       else
         ohai "`brew cleanup` has not been run in the last #{CLEANUP_DEFAULT_DAYS} days, running now..."
-        clean!(quiet: true, periodic: true)
       end
+
+      return if dry_run?
+
+      clean!(quiet: true, periodic: true)
     end
 
     def clean!(quiet: false, periodic: false)
diff --git a/Library/Homebrew/cmd/install.rb b/Library/Homebrew/cmd/install.rb
index 0b4f433b1d..371432d8ce 100644
--- a/Library/Homebrew/cmd/install.rb
+++ b/Library/Homebrew/cmd/install.rb
@@ -27,8 +27,14 @@ module Homebrew
         Install a <formula> or <cask>. Additional options specific to a <formula> may be
         appended to the command.
 
+        Unless `HOMEBREW_NO_INSTALLED_DEPENDENTS_CHECK` is set, `brew upgrade` or `brew reinstall` will be run for
+        outdated dependents and dependents with broken linkage, respectively.
+
         Unless `HOMEBREW_NO_INSTALL_CLEANUP` is set, `brew cleanup` will then be run for
         the installed formulae or, every 30 days, for all formulae.
+
+        Unless `HOMEBREW_NO_INSTALL_UPGRADE` is set, `brew install <formula>` will upgrade <formula> if it
+        is already installed but outdated.
       EOS
       switch "-d", "--debug",
              description: "If brewing fails, open an interactive debugging session with access to IRB " \
diff --git a/Library/Homebrew/cmd/reinstall.rb b/Library/Homebrew/cmd/reinstall.rb
index c29675f3f7..9bceda66b2 100644
--- a/Library/Homebrew/cmd/reinstall.rb
+++ b/Library/Homebrew/cmd/reinstall.rb
@@ -26,6 +26,9 @@ module Homebrew
         Uninstall and then reinstall a <formula> or <cask> using the same options it was
         originally installed with, plus any appended options specific to a <formula>.
 
+        Unless `HOMEBREW_NO_INSTALLED_DEPENDENTS_CHECK` is set, `brew upgrade` or `brew reinstall` will be run for
+        outdated dependents and dependents with broken linkage, respectively.
+
         Unless `HOMEBREW_NO_INSTALL_CLEANUP` is set, `brew cleanup` will then be run for the
         reinstalled formulae or, every 30 days, for all formulae.
       EOS
diff --git a/Library/Homebrew/cmd/upgrade.rb b/Library/Homebrew/cmd/upgrade.rb
index 6c4514acd1..b7fa29b427 100644
--- a/Library/Homebrew/cmd/upgrade.rb
+++ b/Library/Homebrew/cmd/upgrade.rb
@@ -23,6 +23,9 @@ module Homebrew
         installed with, plus any appended brew formula options. If <cask> or <formula> are specified,
         upgrade only the given <cask> or <formula> kegs (unless they are pinned; see `pin`, `unpin`).
 
+        Unless `HOMEBREW_NO_INSTALLED_DEPENDENTS_CHECK` is set, `brew upgrade` or `brew reinstall` will be run for
+        outdated dependents and dependents with broken linkage, respectively.
+
         Unless `HOMEBREW_NO_INSTALL_CLEANUP` is set, `brew cleanup` will then be run for the
         upgraded formulae or, every 30 days, for all formulae.
       EOS
diff --git a/Library/Homebrew/dev-cmd/pr-pull.rb b/Library/Homebrew/dev-cmd/pr-pull.rb
index f6b431f625..fa5050ffc7 100644
--- a/Library/Homebrew/dev-cmd/pr-pull.rb
+++ b/Library/Homebrew/dev-cmd/pr-pull.rb
@@ -301,7 +301,7 @@ module Homebrew
 
   def changed_formulae(tap, original_commit)
     if Homebrew::EnvConfig.disable_load_formula?
-      opoo "Can't check if updated bottles are necessary as formula loading is disabled!"
+      opoo "Can't check if updated bottles are necessary as HOMEBREW_DISABLE_LOAD_FORMULA is set!"
       return
     end
 
diff --git a/Library/Homebrew/download_strategy.rb b/Library/Homebrew/download_strategy.rb
index 0182eaf713..237d7753df 100644
--- a/Library/Homebrew/download_strategy.rb
+++ b/Library/Homebrew/download_strategy.rb
@@ -520,7 +520,7 @@ class CurlDownloadStrategy < AbstractFileDownloadStrategy
 
     if Homebrew::EnvConfig.no_insecure_redirect? &&
        url.start_with?("https://") && !resolved_url.start_with?("https://")
-      $stderr.puts "HTTPS to HTTP redirect detected & HOMEBREW_NO_INSECURE_REDIRECT is set."
+      $stderr.puts "HTTPS to HTTP redirect detected and HOMEBREW_NO_INSECURE_REDIRECT is set."
       raise CurlDownloadStrategyError, url
     end
 
@@ -1029,6 +1029,7 @@ class GitHubGitDownloadStrategy < GitDownloadStrategy
   end
 
   def github_last_commit
+    # TODO: move to Utils::GitHub
     return if Homebrew::EnvConfig.no_github_api?
 
     output, _, status = curl_output(
@@ -1045,6 +1046,7 @@ class GitHubGitDownloadStrategy < GitDownloadStrategy
   end
 
   def multiple_short_commits_exist?(commit)
+    # TODO: move to Utils::GitHub
     return if Homebrew::EnvConfig.no_github_api?
 
     output, _, status = curl_output(
diff --git a/Library/Homebrew/env_config.rb b/Library/Homebrew/env_config.rb
index 007b80a302..4eececa008 100644
--- a/Library/Homebrew/env_config.rb
+++ b/Library/Homebrew/env_config.rb
@@ -26,7 +26,9 @@ module Homebrew
                      "`http://localhost:8080/example.com/foo.tar.gz`.",
       },
       HOMEBREW_AUTO_UPDATE_SECS:               {
-        description: "Automatically check for updates once per this seconds interval.",
+        description: "Run `brew update` once every `HOMEBREW_AUTO_UPDATE_SECS` seconds before some commands, " \
+                     "e.g. `brew install`, `brew upgrade` and `brew tap`. Alternatively, " \
+                     "disable auto-update entirely with HOMEBREW_NO_AUTO_UPDATE.",
         default:     300,
       },
       HOMEBREW_BAT:                            {
@@ -221,8 +223,9 @@ module Homebrew
         boolean:     true,
       },
       HOMEBREW_NO_AUTO_UPDATE:                 {
-        description: "If set, do not automatically update before running some commands e.g. " \
-                     "`brew install`, `brew upgrade` and `brew tap`.",
+        description: "If set, do not automatically update before running some commands, e.g. " \
+                     "`brew install`, `brew upgrade` and `brew tap`. Alternatively, " \
+                     "run this less often by setting HOMEBREW_AUTO_UPDATE_SECS to a value higher than the default.",
         boolean:     true,
       },
       HOMEBREW_NO_BOOTSNAP:                    {
@@ -230,8 +233,10 @@ module Homebrew
         boolean:     true,
       },
       HOMEBREW_NO_INSTALLED_DEPENDENTS_CHECK:  {
-        description: "If set, do not check for broken dependents after installing, upgrading or reinstalling " \
-                     "formulae.",
+        description: "If set, do not check for broken linkage of dependents or outdated dependents after " \
+                     "installing, upgrading or reinstalling formulae. This will result in fewer dependents " \
+                     " (and their dependencies) being upgraded or reinstalled but may result in more breakage " \
+                     "from running `brew install <formula>` or `brew upgrade <formula>`.",
         boolean:     true,
       },
       HOMEBREW_NO_CLEANUP_FORMULAE:            {
@@ -266,11 +271,13 @@ module Homebrew
       HOMEBREW_NO_INSTALL_CLEANUP:             {
         description: "If set, `brew install`, `brew upgrade` and `brew reinstall` will never automatically " \
                      "cleanup installed/upgraded/reinstalled formulae or all formulae every " \
-                     "`HOMEBREW_CLEANUP_PERIODIC_FULL_DAYS` days.",
+                     "`HOMEBREW_CLEANUP_PERIODIC_FULL_DAYS` days. Alternatively, HOMEBREW_NO_CLEANUP_FORMULAE " \
+                     "allows specifying specific formulae to not clean up.",
         boolean:     true,
       },
       HOMEBREW_NO_INSTALL_UPGRADE:             {
-        description: "If set, `brew install` will not automatically upgrade installed but outdated formulae",
+        description: "If set, `brew install <formula>` will not upgrade `<formula>` if it is installed but " \
+                     "outdated.",
         boolean:     true,
       },
       HOMEBREW_PRY:                            {
diff --git a/Library/Homebrew/formula_installer.rb b/Library/Homebrew/formula_installer.rb
index 451f779b37..7a2f1b801f 100644
--- a/Library/Homebrew/formula_installer.rb
+++ b/Library/Homebrew/formula_installer.rb
@@ -1302,7 +1302,8 @@ class FormulaInstaller
       next unless SPDX.licenses_forbid_installation? dep_f.license, forbidden_licenses
 
       raise CannotInstallFormulaError, <<~EOS
-        The installation of #{formula.name} has a dependency on #{dep.name} where all its licenses are forbidden:
+        The installation of #{formula.name} has a dependency on #{dep.name} where all
+        its licenses are forbidden by HOMEBREW_FORBIDDEN_LICENSES:
           #{SPDX.license_expression_to_string dep_f.license}.
       EOS
     end
@@ -1312,7 +1313,8 @@ class FormulaInstaller
     return unless SPDX.licenses_forbid_installation? formula.license, forbidden_licenses
 
     raise CannotInstallFormulaError, <<~EOS
-      #{formula.name}'s licenses are all forbidden: #{SPDX.license_expression_to_string formula.license}.
+      #{formula.name}'s licenses are all forbidden by HOMEBREW_FORBIDDEN_LICENSES:
+        #{SPDX.license_expression_to_string formula.license}.
     EOS
   end
 end
diff --git a/Library/Homebrew/install.rb b/Library/Homebrew/install.rb
index 4b4dea724b..24b02c78e9 100644
--- a/Library/Homebrew/install.rb
+++ b/Library/Homebrew/install.rb
@@ -125,7 +125,10 @@ module Homebrew
         # dependencies. Therefore before performing other checks we need to be
         # sure --force flag is passed.
         if f.outdated?
-          return true unless Homebrew::EnvConfig.no_install_upgrade?
+          unless Homebrew::EnvConfig.no_install_upgrade?
+            puts "#{f.name} #{f.linked_version} is already installed but outdated (so it will be upgraded)."
+            return true
+          end
 
           optlinked_version = Keg.for(f.opt_prefix).version
           onoe <<~EOS
@@ -213,7 +216,7 @@ module Homebrew
         message = "#{f.name} #{f.linked_version} is already installed"
         if f.outdated? && !head
           unless Homebrew::EnvConfig.no_install_upgrade?
-            puts "#{message} but outdated"
+            puts "#{message} but outdated (so it will be upgraded)."
             return true
           end
 
diff --git a/Library/Homebrew/manpages/brew.1.md.erb b/Library/Homebrew/manpages/brew.1.md.erb
index b2ce261cea..008fe22250 100644
--- a/Library/Homebrew/manpages/brew.1.md.erb
+++ b/Library/Homebrew/manpages/brew.1.md.erb
@@ -57,6 +57,8 @@ For the full command list, see the [COMMANDS](#commands) section.
 With `--verbose` or `--debug`, many commands print extra debugging information.
 Note that these options should only appear after a command.
 
+Some command behaviour can be customised with environment variables; see the [ENVIRONMENT](#environment) section.
+
 ### `install` <formula>
 
 Install <formula>.
diff --git a/Library/Homebrew/upgrade.rb b/Library/Homebrew/upgrade.rb
index a8073ff57f..7fe95653a6 100644
--- a/Library/Homebrew/upgrade.rb
+++ b/Library/Homebrew/upgrade.rb
@@ -318,6 +318,7 @@ module Homebrew
 
       # Assess the dependents tree again now we've upgraded.
       oh1 "Checking for dependents of upgraded formulae..." unless dry_run
+
       broken_dependents = check_broken_dependents(installed_formulae)
       if broken_dependents.blank?
         if dry_run
@@ -354,7 +355,7 @@ module Homebrew
       else
         count = reinstallable_broken_dependents.count
         plural = "dependent".pluralize(reinstallable_broken_dependents.count)
-        ohai "Reinstalling #{count} broken #{plural} from source:"
+        ohai "Reinstalling #{count} #{plural} with broken linkage from source:"
         puts reinstallable_broken_dependents.map(&:full_specified_name)
                                             .join(", ")
       end
diff --git a/docs/Manpage.md b/docs/Manpage.md
index a9b59a4942..5d3bd7640e 100644
--- a/docs/Manpage.md
+++ b/docs/Manpage.md
@@ -41,6 +41,8 @@ For the full command list, see the [COMMANDS](#commands) section.
 With `--verbose` or `--debug`, many commands print extra debugging information.
 Note that these options should only appear after a command.
 
+Some command behaviour can be customised with environment variables; see the [ENVIRONMENT](#environment) section.
+
 ### `install` *`formula`*
 
 Install *`formula`*.
@@ -301,9 +303,15 @@ If a *`formula`* or *`cask`* is provided, show summary of information about it.
 Install a *`formula`* or *`cask`*. Additional options specific to a *`formula`* may be
 appended to the command.
 
+Unless `HOMEBREW_NO_INSTALLED_DEPENDENTS_CHECK` is set, `brew upgrade` or `brew reinstall` will be run for
+outdated dependents and dependents with broken linkage, respectively.
+
 Unless `HOMEBREW_NO_INSTALL_CLEANUP` is set, `brew cleanup` will then be run for
 the installed formulae or, every 30 days, for all formulae.
 
+Unless `HOMEBREW_NO_INSTALL_UPGRADE` is set, `brew install *`formula`*` will upgrade *`formula`* if it
+is already installed but outdated.
+
 * `-d`, `--debug`:
   If brewing fails, open an interactive debugging session with access to IRB or a shell inside the temporary build directory.
 * `-f`, `--force`:
@@ -507,6 +515,9 @@ all items or checking if any current formulae/casks have Ruby issues.
 Uninstall and then reinstall a *`formula`* or *`cask`* using the same options it was
 originally installed with, plus any appended options specific to a *`formula`*.
 
+Unless `HOMEBREW_NO_INSTALLED_DEPENDENTS_CHECK` is set, `brew upgrade` or `brew reinstall` will be run for
+outdated dependents and dependents with broken linkage, respectively.
+
 Unless `HOMEBREW_NO_INSTALL_CLEANUP` is set, `brew cleanup` will then be run for the
 reinstalled formulae or, every 30 days, for all formulae.
 
@@ -683,6 +694,9 @@ Upgrade outdated casks and outdated, unpinned formulae using the same options th
 installed with, plus any appended brew formula options. If *`cask`* or *`formula`* are specified,
 upgrade only the given *`cask`* or *`formula`* kegs (unless they are pinned; see `pin`, `unpin`).
 
+Unless `HOMEBREW_NO_INSTALLED_DEPENDENTS_CHECK` is set, `brew upgrade` or `brew reinstall` will be run for
+outdated dependents and dependents with broken linkage, respectively.
+
 Unless `HOMEBREW_NO_INSTALL_CLEANUP` is set, `brew cleanup` will then be run for the
 upgraded formulae or, every 30 days, for all formulae.
 
@@ -1898,7 +1912,7 @@ example, run `export HOMEBREW_NO_INSECURE_REDIRECT=1` rather than just
   <br>Prefix all download URLs, including those for bottles, with this value. For example, `HOMEBREW_ARTIFACT_DOMAIN=http://localhost:8080` will cause a formula with the URL `https://example.com/foo.tar.gz` to instead download from `http://localhost:8080/example.com/foo.tar.gz`.
 
 - `HOMEBREW_AUTO_UPDATE_SECS`
-  <br>Automatically check for updates once per this seconds interval.
+  <br>Run `brew update` once every `HOMEBREW_AUTO_UPDATE_SECS` seconds before some commands, e.g. `brew install`, `brew upgrade` and `brew tap`. Alternatively, disable auto-update entirely with HOMEBREW_NO_AUTO_UPDATE.
 
   *Default:* `300`.
 
@@ -2057,13 +2071,13 @@ example, run `export HOMEBREW_NO_INSECURE_REDIRECT=1` rather than just
   <br>If set, do not send analytics. For more information, see: <https://docs.brew.sh/Analytics>
 
 - `HOMEBREW_NO_AUTO_UPDATE`
-  <br>If set, do not automatically update before running some commands e.g. `brew install`, `brew upgrade` and `brew tap`.
+  <br>If set, do not automatically update before running some commands, e.g. `brew install`, `brew upgrade` and `brew tap`. Alternatively, run this less often by setting HOMEBREW_AUTO_UPDATE_SECS to a value higher than the default.
 
 - `HOMEBREW_NO_BOOTSNAP`
   <br>If set, do not use Bootsnap to speed up repeated `brew` calls.
 
 - `HOMEBREW_NO_INSTALLED_DEPENDENTS_CHECK`
-  <br>If set, do not check for broken dependents after installing, upgrading or reinstalling formulae.
+  <br>If set, do not check for broken linkage of dependents or outdated dependents after installing, upgrading or reinstalling formulae. This will result in fewer dependents  (and their dependencies) being upgraded or reinstalled but may result in more breakage from running `brew install *`formula`*` or `brew upgrade *`formula`*`.
 
 - `HOMEBREW_NO_CLEANUP_FORMULAE`
   <br>A comma-separated list of formulae. Homebrew will refuse to clean up a formula if it appears on this list.
@@ -2090,10 +2104,10 @@ example, run `export HOMEBREW_NO_INSECURE_REDIRECT=1` rather than just
     *Note:* While ensuring your downloads are fully secure, this is likely to cause from-source SourceForge, some GNU & GNOME-hosted formulae to fail to download.
 
 - `HOMEBREW_NO_INSTALL_CLEANUP`
-  <br>If set, `brew install`, `brew upgrade` and `brew reinstall` will never automatically cleanup installed/upgraded/reinstalled formulae or all formulae every `HOMEBREW_CLEANUP_PERIODIC_FULL_DAYS` days.
+  <br>If set, `brew install`, `brew upgrade` and `brew reinstall` will never automatically cleanup installed/upgraded/reinstalled formulae or all formulae every `HOMEBREW_CLEANUP_PERIODIC_FULL_DAYS` days. Alternatively, HOMEBREW_NO_CLEANUP_FORMULAE allows specifying specific formulae to not clean up.
 
 - `HOMEBREW_NO_INSTALL_UPGRADE`
-  <br>If set, `brew install` will not automatically upgrade installed but outdated formulae
+  <br>If set, `brew install *`formula`*` will not upgrade `*`formula`*` if it is installed but outdated.
 
 - `HOMEBREW_PRY`
   <br>If set, use Pry for the `brew irb` command.
diff --git a/manpages/brew.1 b/manpages/brew.1
index a4fcbd823b..0b5c70f663 100644
--- a/manpages/brew.1
+++ b/manpages/brew.1
@@ -61,6 +61,9 @@ For the full command list, see the \fICOMMANDS\fR section\.
 .P
 With \fB\-\-verbose\fR or \fB\-\-debug\fR, many commands print extra debugging information\. Note that these options should only appear after a command\.
 .
+.P
+Some command behaviour can be customised with environment variables; see the \fIENVIRONMENT\fR section\.
+.
 .SS "\fBinstall\fR \fIformula\fR"
 Install \fIformula\fR\.
 .
@@ -389,8 +392,14 @@ Treat all named arguments as casks\.
 Install a \fIformula\fR or \fIcask\fR\. Additional options specific to a \fIformula\fR may be appended to the command\.
 .
 .P
+Unless \fBHOMEBREW_NO_INSTALLED_DEPENDENTS_CHECK\fR is set, \fBbrew upgrade\fR or \fBbrew reinstall\fR will be run for outdated dependents and dependents with broken linkage, respectively\.
+.
+.P
 Unless \fBHOMEBREW_NO_INSTALL_CLEANUP\fR is set, \fBbrew cleanup\fR will then be run for the installed formulae or, every 30 days, for all formulae\.
 .
+.P
+Unless \fBHOMEBREW_NO_INSTALL_UPGRADE\fR is set, \fBbrew install <formula>\fR will upgrade \fIformula\fR if it is already installed but outdated\.
+.
 .TP
 \fB\-d\fR, \fB\-\-debug\fR
 If brewing fails, open an interactive debugging session with access to IRB or a shell inside the temporary build directory\.
@@ -691,6 +700,9 @@ Syntax\-check all of Homebrew\'s Ruby files (if no \fB<tap>\fR is passed)\.
 Uninstall and then reinstall a \fIformula\fR or \fIcask\fR using the same options it was originally installed with, plus any appended options specific to a \fIformula\fR\.
 .
 .P
+Unless \fBHOMEBREW_NO_INSTALLED_DEPENDENTS_CHECK\fR is set, \fBbrew upgrade\fR or \fBbrew reinstall\fR will be run for outdated dependents and dependents with broken linkage, respectively\.
+.
+.P
 Unless \fBHOMEBREW_NO_INSTALL_CLEANUP\fR is set, \fBbrew cleanup\fR will then be run for the reinstalled formulae or, every 30 days, for all formulae\.
 .
 .TP
@@ -933,6 +945,9 @@ Fetch and reset Homebrew and all tap repositories (or any specified \fIrepositor
 Upgrade outdated casks and outdated, unpinned formulae using the same options they were originally installed with, plus any appended brew formula options\. If \fIcask\fR or \fIformula\fR are specified, upgrade only the given \fIcask\fR or \fIformula\fR kegs (unless they are pinned; see \fBpin\fR, \fBunpin\fR)\.
 .
 .P
+Unless \fBHOMEBREW_NO_INSTALLED_DEPENDENTS_CHECK\fR is set, \fBbrew upgrade\fR or \fBbrew reinstall\fR will be run for outdated dependents and dependents with broken linkage, respectively\.
+.
+.P
 Unless \fBHOMEBREW_NO_INSTALL_CLEANUP\fR is set, \fBbrew cleanup\fR will then be run for the upgraded formulae or, every 30 days, for all formulae\.
 .
 .TP
@@ -2684,7 +2699,7 @@ Prefix all download URLs, including those for bottles, with this value\. For exa
 \fBHOMEBREW_AUTO_UPDATE_SECS\fR
 .
 .br
-Automatically check for updates once per this seconds interval\.
+Run \fBbrew update\fR once every \fBHOMEBREW_AUTO_UPDATE_SECS\fR seconds before some commands, e\.g\. \fBbrew install\fR, \fBbrew upgrade\fR and \fBbrew tap\fR\. Alternatively, disable auto\-update entirely with HOMEBREW_NO_AUTO_UPDATE\.
 .
 .IP
 \fIDefault:\fR \fB300\fR\.
@@ -2981,7 +2996,7 @@ If set, do not send analytics\. For more information, see: \fIhttps://docs\.brew
 \fBHOMEBREW_NO_AUTO_UPDATE\fR
 .
 .br
-If set, do not automatically update before running some commands e\.g\. \fBbrew install\fR, \fBbrew upgrade\fR and \fBbrew tap\fR\.
+If set, do not automatically update before running some commands, e\.g\. \fBbrew install\fR, \fBbrew upgrade\fR and \fBbrew tap\fR\. Alternatively, run this less often by setting HOMEBREW_AUTO_UPDATE_SECS to a value higher than the default\.
 .
 .TP
 \fBHOMEBREW_NO_BOOTSNAP\fR
@@ -2993,7 +3008,7 @@ If set, do not use Bootsnap to speed up repeated \fBbrew\fR calls\.
 \fBHOMEBREW_NO_INSTALLED_DEPENDENTS_CHECK\fR
 .
 .br
-If set, do not check for broken dependents after installing, upgrading or reinstalling formulae\.
+If set, do not check for broken linkage of dependents or outdated dependents after installing, upgrading or reinstalling formulae\. This will result in fewer dependents (and their dependencies) being upgraded or reinstalled but may result in more breakage from running \fBbrew install <formula>\fR or \fBbrew upgrade <formula>\fR\.
 .
 .TP
 \fBHOMEBREW_NO_CLEANUP_FORMULAE\fR
@@ -3044,13 +3059,13 @@ If set, forbid redirects from secure HTTPS to insecure HTTP\.
 \fBHOMEBREW_NO_INSTALL_CLEANUP\fR
 .
 .br
-If set, \fBbrew install\fR, \fBbrew upgrade\fR and \fBbrew reinstall\fR will never automatically cleanup installed/upgraded/reinstalled formulae or all formulae every \fBHOMEBREW_CLEANUP_PERIODIC_FULL_DAYS\fR days\.
+If set, \fBbrew install\fR, \fBbrew upgrade\fR and \fBbrew reinstall\fR will never automatically cleanup installed/upgraded/reinstalled formulae or all formulae every \fBHOMEBREW_CLEANUP_PERIODIC_FULL_DAYS\fR days\. Alternatively, HOMEBREW_NO_CLEANUP_FORMULAE allows specifying specific formulae to not clean up\.
 .
 .TP
 \fBHOMEBREW_NO_INSTALL_UPGRADE\fR
 .
 .br
-If set, \fBbrew install\fR will not automatically upgrade installed but outdated formulae
+If set, \fBbrew install <formula>\fR will not upgrade \fB<formula>\fR if it is installed but outdated\.
 .
 .TP
 \fBHOMEBREW_PRY\fR