diff --git a/.github/workflows/linux.yml b/.github/workflows/linux.yml
index a11aa08e6..e2e19083b 100644
--- a/.github/workflows/linux.yml
+++ b/.github/workflows/linux.yml
@@ -1,14 +1,16 @@
 # Thorough linux CI tests: build, test, benchmark, haddock &
 # run functional tests, with all supported GHC versions.
 #
-# Runs: periodically, on notable pull request to master, and on
-# notable push to master or ci-linux.
+# Runs: periodically on master, on notable pull request to master, and
+# on notable push to ci-linux or master.
 
 name: linux full CI
 
 on:
+  # Scheduled workflows run on the latest commit on the default or base branch. (master)
   schedule:
   - cron: "0 07 * * 0"  # sunday midnight pacific
+
   pull_request:
     branches: [ master ]
     paths:
@@ -24,6 +26,7 @@ on:
       - '!**.5'
       - '!**.info'
       - '!**.txt'
+
   push:
     branches: [ master, ci-linux ]
     paths:
@@ -211,7 +214,6 @@ jobs:
         ARGS: ${{ matrix.plan.args }}
 
     - name: Test haddock generation
-      shell: bash
       run: |
         time stack $ARGS build --fast --haddock --no-haddock-deps --no-haddock-hyperlink-source --haddock-arguments="--no-print-missing-docs"
       # --no-haddock-hyperlink-source is 25% faster
diff --git a/.github/workflows/mac.yml b/.github/workflows/mac.yml
index 236470508..59675eea7 100644
--- a/.github/workflows/mac.yml
+++ b/.github/workflows/mac.yml
@@ -1,12 +1,13 @@
 # Light Mac CI tests: build and run functional tests with one GHC version.
 #
-# Runs: periodically, and on notable push to ci-mac.
+# Runs: periodically on master, and on notable push to ci-mac.
 
 name: mac CI
 
 on:
   schedule:
   - cron: "0 07 * * 0"  # sunday midnight pacific
+
   push:
     branches: [ ci-mac ]
     paths:
diff --git a/.github/workflows/windows.yml b/.github/workflows/windows.yml
index fcddacbb3..ee7749c08 100644
--- a/.github/workflows/windows.yml
+++ b/.github/workflows/windows.yml
@@ -1,13 +1,14 @@
-# Light Mac CI tests: build and run functional tests with one GHC version.
+# Light Windows CI tests: build and run functional tests with one GHC version.
 # GHC 8.8.2 for now to avoid https://gitlab.haskell.org/ghc/ghc/issues/17926.
 #
-# Runs: periodically, and on notable push to ci-windows.
+# Runs: periodically on master, and on notable push to ci-windows.
 
 name: windows CI
 
 on:
   schedule:
   - cron: "0 07 * * 0"  # sunday midnight pacific
+
   push:
     branches: [ ci-windows ]
     paths: