diff --git a/.github/workflows/build-clang.yml b/.github/workflows/build-clang.yml
index 65a7c28d..0a4969a9 100644
--- a/.github/workflows/build-clang.yml
+++ b/.github/workflows/build-clang.yml
@@ -1,6 +1,6 @@
 on:
   push:
-    branches: [ master,release_branch* ]
+    branches: [ release_branch* ]
   pull_request:
     branches: [ master,release_branch* ]
   workflow_dispatch:
diff --git a/.github/workflows/build-msi-package.yml b/.github/workflows/build-msi-package.yml
index 76ffa648..9ebd04d6 100644
--- a/.github/workflows/build-msi-package.yml
+++ b/.github/workflows/build-msi-package.yml
@@ -1,6 +1,6 @@
 on:
   push:
-    branches: [ master,release_branch* ]
+    branches: [ release_branch* ]
   pull_request:
     branches: [ master,release_branch* ]
   workflow_dispatch:
diff --git a/.github/workflows/build-multi-static.yml b/.github/workflows/build-multi-static.yml
index d2de2da0..494aa213 100644
--- a/.github/workflows/build-multi-static.yml
+++ b/.github/workflows/build-multi-static.yml
@@ -1,6 +1,9 @@
 on:
   push:
-    branches: [ master,release_branch* ]
+    branches: [ release_branch* ]
+  # Weekly master build keeps the PR ccache warm (unused caches expire after 7 days).
+  schedule:
+    - cron: '47 3 * * 1'
   pull_request:
     branches: [ master,release_branch* ]
   workflow_dispatch:
diff --git a/.github/workflows/build-multi.yml b/.github/workflows/build-multi.yml
index ec955ce7..aac62cab 100644
--- a/.github/workflows/build-multi.yml
+++ b/.github/workflows/build-multi.yml
@@ -1,6 +1,9 @@
 on:
   push:
-    branches: [ master,release_branch* ]
+    branches: [ release_branch* ]
+  # Weekly master build keeps the PR ccache warm (unused caches expire after 7 days).
+  schedule:
+    - cron: '17 3 * * 1'
   pull_request:
     branches: [ master,release_branch* ]
   workflow_dispatch:
diff --git a/.github/workflows/build-quick-static-n-1.yml b/.github/workflows/build-quick-static-n-1.yml
index c38bc097..06513903 100644
--- a/.github/workflows/build-quick-static-n-1.yml
+++ b/.github/workflows/build-quick-static-n-1.yml
@@ -1,6 +1,9 @@
 on:
   push:
-    branches: [ master,release_branch* ]
+    branches: [ release_branch* ]
+  # Weekly master build keeps the PR ccache warm (unused caches expire after 7 days).
+  schedule:
+    - cron: '47 4 * * 1'
   pull_request:
     branches: [ master,release_branch* ]
   workflow_dispatch:
diff --git a/.github/workflows/build-quick-static.yml b/.github/workflows/build-quick-static.yml
index 09ae1b31..6588b38b 100644
--- a/.github/workflows/build-quick-static.yml
+++ b/.github/workflows/build-quick-static.yml
@@ -1,6 +1,9 @@
 on:
   push:
-    branches: [ master,release_branch* ]
+    branches: [ release_branch* ]
+  # Weekly master build keeps the PR ccache warm (unused caches expire after 7 days).
+  schedule:
+    - cron: '17 4 * * 1'
   pull_request:
     branches: [ master,release_branch* ]
   workflow_dispatch:
diff --git a/.github/workflows/build-quick.yml b/.github/workflows/build-quick.yml
index 23764f56..a7234323 100644
--- a/.github/workflows/build-quick.yml
+++ b/.github/workflows/build-quick.yml
@@ -1,6 +1,6 @@
 on:
   push:
-    branches: [ master,release_branch* ]
+    branches: [ release_branch* ]
   pull_request:
     branches: [ master,release_branch* ]
   workflow_dispatch:
diff --git a/.github/workflows/check-abi.yml b/.github/workflows/check-abi.yml
index 165c4011..a82892e9 100644
--- a/.github/workflows/check-abi.yml
+++ b/.github/workflows/check-abi.yml
@@ -1,6 +1,7 @@
 on:
   pull_request:
     branches: [master]
+  workflow_dispatch:
 
 permissions: read-all
 
@@ -94,7 +95,7 @@ jobs:
     - name: Checkout base
       uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
       with:
-        ref: ${{ github.base_ref }}
+        ref: ${{ github.base_ref || 'master' }}
         clean: true
         path: base
     - name: Checkout head
diff --git a/.github/workflows/codespell.yml b/.github/workflows/codespell.yml
index 29e8dc4f..78032d96 100644
--- a/.github/workflows/codespell.yml
+++ b/.github/workflows/codespell.yml
@@ -11,6 +11,7 @@ name: Codespell
 on:
   pull_request:
     branches: [master]
+  workflow_dispatch:
 
 permissions:
   contents: read
diff --git a/.github/workflows/regen-source.yml b/.github/workflows/regen-source.yml
index a3e78971..8a42c2cb 100644
--- a/.github/workflows/regen-source.yml
+++ b/.github/workflows/regen-source.yml
@@ -18,7 +18,7 @@ name: Regenerate Source
 
 on:
   push:
-    branches: [ master,release_branch* ]
+    branches: [ release_branch* ]
   pull_request:
     branches: [ master,release_branch* ]
   workflow_dispatch: