diff --git a/.github/workflows/documentation.yml b/.github/workflows/documentation.yml
index 3eadbaa..e2d008c 100644
--- a/.github/workflows/documentation.yml
+++ b/.github/workflows/documentation.yml
@@ -38,7 +38,7 @@ on:
         type: string
       cache:
         description: "Use the julia-actions/cache action for caching"
-        default: true
+        default: false
         required: false
         type: boolean
       coverage:
diff --git a/.github/workflows/downstream.yml b/.github/workflows/downstream.yml
index 8a6144f..0cabd9a 100644
--- a/.github/workflows/downstream.yml
+++ b/.github/workflows/downstream.yml
@@ -38,7 +38,7 @@ on:
         type: string
       cache:
         description: "Use the julia-actions/cache action for caching"
-        default: true
+        default: false
         required: false
         type: boolean
       buildpkg:
diff --git a/.github/workflows/grouped-tests.yml b/.github/workflows/grouped-tests.yml
index cf61a6e..f1fd8e6 100644
--- a/.github/workflows/grouped-tests.yml
+++ b/.github/workflows/grouped-tests.yml
@@ -69,6 +69,11 @@ on:
         default: "v1"
         required: false
         type: string
+      cache:
+        description: "Use the julia-actions/cache action for caching"
+        default: false
+        required: false
+        type: boolean
 
 jobs:
   detect:
@@ -116,4 +121,5 @@ jobs:
       coverage-directories: "${{ inputs.coverage-directories }}"
       apt-packages: "${{ inputs.apt-packages }}"
       container: "${{ inputs.container }}"
+      cache: ${{ inputs.cache }}
     secrets: "inherit"
diff --git a/.github/workflows/sublibrary-project-tests.yml b/.github/workflows/sublibrary-project-tests.yml
index cfaad20..6958b14 100644
--- a/.github/workflows/sublibrary-project-tests.yml
+++ b/.github/workflows/sublibrary-project-tests.yml
@@ -61,6 +61,11 @@ on:
         default: "v1"
         required: false
         type: string
+      cache:
+        description: "Use the julia-actions/cache action for caching"
+        default: false
+        required: false
+        type: boolean
 
 jobs:
   detect:
@@ -126,4 +131,5 @@ jobs:
       allow-reresolve: ${{ inputs.allow-reresolve }}
       coverage: ${{ inputs.coverage }}
       coverage-directories: "${{ matrix.project }}/src,${{ matrix.project }}/ext"
+      cache: ${{ inputs.cache }}
     secrets: "inherit"
diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 00ce11f..d0f040f 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -39,7 +39,7 @@ on:
         type: string
       cache:
         description: "Use the julia-actions/cache action for caching"
-        default: true
+        default: false
         required: false
         type: boolean
       buildpkg:
@@ -124,7 +124,11 @@ jobs:
           arch: "${{ inputs.julia-arch || runner.arch }}"
 
       - uses: julia-actions/cache@v3
-        if: "${{ inputs.cache }}"
+        # Skip caching on self-hosted runners: demeter has a persistent, already
+        # warm depot (20-29GB), so the cache always MISSES and the post-job save
+        # tar-uploads 20-29GB at ~7MB/s (+30-62 min/job). Only useful on
+        # GitHub-hosted/ephemeral runners (empty `runner` and not `self-hosted`).
+        if: "${{ inputs.cache && inputs.runner == '' && !inputs.self-hosted }}"
         with:
           token: "${{ secrets.GITHUB_TOKEN }}"