diff --git a/.github/workflows/cygwin-51x.yml b/.github/workflows/cygwin-51x.yml
index e5b9584ad..8041fa28e 100644
--- a/.github/workflows/cygwin-51x.yml
+++ b/.github/workflows/cygwin-51x.yml
@@ -1,10 +1,9 @@
 name: Cygwin 5.1
 
 on:
-  pull_request:
-  push:
-    branches:
-      - main
+  schedule:
+    # Every Sunday morning, at 2:22 UTC
+    - cron: '22 2 * * 0'
   workflow_dispatch:
 
 jobs:
diff --git a/.github/workflows/linux-51x-32bit.yml b/.github/workflows/linux-51x-32bit.yml
index e0a23930a..160f441c9 100644
--- a/.github/workflows/linux-51x-32bit.yml
+++ b/.github/workflows/linux-51x-32bit.yml
@@ -1,10 +1,9 @@
 name: 32bit 5.1
 
 on:
-  pull_request:
-  push:
-    branches:
-      - main
+  schedule:
+    # Every Sunday morning, at 2:22 UTC
+    - cron: '22 2 * * 0'
   workflow_dispatch:
 
 jobs:
diff --git a/.github/workflows/linux-51x-bytecode.yml b/.github/workflows/linux-51x-bytecode.yml
index 4f75ad56b..83532df3c 100644
--- a/.github/workflows/linux-51x-bytecode.yml
+++ b/.github/workflows/linux-51x-bytecode.yml
@@ -1,10 +1,9 @@
 name: Bytecode 5.1
 
 on:
-  pull_request:
-  push:
-    branches:
-      - main
+  schedule:
+    # Every Sunday morning, at 2:22 UTC
+    - cron: '22 2 * * 0'
   workflow_dispatch:
 
 jobs:
diff --git a/.github/workflows/linux-51x-debug.yml b/.github/workflows/linux-51x-debug.yml
index baebd4650..5a0ae1591 100644
--- a/.github/workflows/linux-51x-debug.yml
+++ b/.github/workflows/linux-51x-debug.yml
@@ -1,10 +1,9 @@
 name: Linux 5.1 debug
 
 on:
-  pull_request:
-  push:
-    branches:
-      - main
+  schedule:
+    # Every Sunday morning, at 2:22 UTC
+    - cron: '22 2 * * 0'
   workflow_dispatch:
 
 jobs:
diff --git a/.github/workflows/linux-51x-fp.yml b/.github/workflows/linux-51x-fp.yml
index 88da7057c..c98fc25eb 100644
--- a/.github/workflows/linux-51x-fp.yml
+++ b/.github/workflows/linux-51x-fp.yml
@@ -1,10 +1,9 @@
 name: FP 5.1
 
 on:
-  pull_request:
-  push:
-    branches:
-      - main
+  schedule:
+    # Every Sunday morning, at 2:22 UTC
+    - cron: '22 2 * * 0'
   workflow_dispatch:
 
 jobs:
diff --git a/.github/workflows/linux-51x.yml b/.github/workflows/linux-51x.yml
index 44ea82c05..bcc5624f6 100644
--- a/.github/workflows/linux-51x.yml
+++ b/.github/workflows/linux-51x.yml
@@ -1,10 +1,9 @@
 name: Linux 5.1
 
 on:
-  pull_request:
-  push:
-    branches:
-      - main
+  schedule:
+    # Every Sunday morning, at 2:22 UTC
+    - cron: '22 2 * * 0'
   workflow_dispatch:
 
 jobs:
diff --git a/.github/workflows/macosx-51x.yml b/.github/workflows/macosx-51x.yml
index 8dbb87005..dec10c5e5 100644
--- a/.github/workflows/macosx-51x.yml
+++ b/.github/workflows/macosx-51x.yml
@@ -1,10 +1,9 @@
 name: macOS 5.1
 
 on:
-  pull_request:
-  push:
-    branches:
-      - main
+  schedule:
+    # Every Sunday morning, at 2:22 UTC
+    - cron: '22 2 * * 0'
   workflow_dispatch:
 
 jobs:
diff --git a/.github/workflows/mingw-51x-bytecode.yml b/.github/workflows/mingw-51x-bytecode.yml
index 596a16b28..bee386453 100644
--- a/.github/workflows/mingw-51x-bytecode.yml
+++ b/.github/workflows/mingw-51x-bytecode.yml
@@ -1,10 +1,9 @@
 name: MinGW bytecode 5.1
 
 on:
-  pull_request:
-  push:
-    branches:
-      - main
+  schedule:
+    # Every Sunday morning, at 2:22 UTC
+    - cron: '22 2 * * 0'
   workflow_dispatch:
 
 jobs:
diff --git a/.github/workflows/mingw-51x.yml b/.github/workflows/mingw-51x.yml
index 03638b722..ba83c6cb8 100644
--- a/.github/workflows/mingw-51x.yml
+++ b/.github/workflows/mingw-51x.yml
@@ -1,10 +1,9 @@
 name: MinGW 5.1
 
 on:
-  pull_request:
-  push:
-    branches:
-      - main
+  schedule:
+    # Every Sunday morning, at 2:22 UTC
+    - cron: '22 2 * * 0'
   workflow_dispatch:
 
 jobs: