diff --git a/.github/workflows/_integration-tests.yml b/.github/workflows/_integration-tests.yml
index 2143e9495..ae7defad2 100644
--- a/.github/workflows/_integration-tests.yml
+++ b/.github/workflows/_integration-tests.yml
@@ -129,7 +129,7 @@ jobs:
 
     integration-tests-bigquery-flaky:
         # we only run this for one python version to avoid running in parallel
-        if: ${{ inputs.package == 'dbt-bigquery' && inputs.python-version == '3.9' }}
+        if: ${{ inputs.package == 'dbt-bigquery' && inputs.python-version == vars.DEFAULT_PYTHON_VERSION }}
         runs-on: ${{ inputs.os }}
         environment:
             name: "dbt-bigquery"
@@ -290,7 +290,7 @@ jobs:
 
     integration-tests-redshift-flaky:
         # we only run this for one python version to avoid running in parallel
-        if: ${{ inputs.package == 'dbt-redshift' && inputs.python-version == '3.9' }}
+        if: ${{ inputs.package == 'dbt-redshift' && inputs.python-version == vars.DEFAULT_PYTHON_VERSION }}
         runs-on: ${{ inputs.os }}
         environment:
             name: "dbt-redshift"
diff --git a/.github/workflows/pull-request-checks.yml b/.github/workflows/pull-request-checks.yml
index 7fcd8f910..b4e224e45 100644
--- a/.github/workflows/pull-request-checks.yml
+++ b/.github/workflows/pull-request-checks.yml
@@ -52,10 +52,8 @@ jobs:
             fail-fast: false
             matrix:
                 package: ${{ fromJSON(needs.affected-packages.outputs.changelog-entry-check) }}
-                os: [ubuntu-22.04]
-                python-version: ["3.9", "3.10", "3.11", "3.12"]
         with:
-            package: "dbt-athena"
+            package: ${{ matrix.package }}
             pull-request: ${{ github.event.pull_request.number }}
         secrets: inherit
 
@@ -73,14 +71,12 @@ jobs:
             fail-fast: false
             matrix:
                 package: ${{ fromJSON(needs.affected-packages.outputs.verify-build) }}
-                os: [ubuntu-22.04, macos-14, windows-2022]
-                python-version: ["3.9", "3.12"]
         with:
             package: ${{ matrix.package }}
             branch: ${{ github.event.pull_request.head.ref }}
             repository: ${{ github.event.pull_request.head.repo.full_name }}
-            os: ${{ matrix.os }}
-            python-version: ${{ matrix.python-version }}
+            os: ${{ vars.DEFAULT_RUNNER }}
+            python-version: ${{ vars.DEFAULT_PYTHON_VERSION }}
 
     unit-tests:
         uses: ./.github/workflows/_unit-tests.yml
@@ -90,14 +86,12 @@ jobs:
             fail-fast: false
             matrix:
                 package: ${{ fromJSON(needs.affected-packages.outputs.unit-tests) }}
-                os: [ubuntu-22.04, macos-14, windows-2022]
-                python-version: ["3.9", "3.12"]
         with:
             package: ${{ matrix.package }}
             branch: ${{ github.event.pull_request.head.ref }}
             repository: ${{ github.event.pull_request.head.repo.full_name }}
-            os: ${{ matrix.os }}
-            python-version: ${{ matrix.python-version }}
+            os: ${{ vars.DEFAULT_RUNNER }}
+            python-version: ${{ vars.DEFAULT_PYTHON_VERSION }}
 
     integration-tests:
         uses: ./.github/workflows/_integration-tests.yml
@@ -107,14 +101,12 @@ jobs:
             fail-fast: false
             matrix:
                 package: ${{ fromJSON(needs.affected-packages.outputs.integration-tests) }}
-                os: [ubuntu-22.04]
-                python-version: ["3.9", "3.12"]
         with:
             package: ${{ matrix.package }}
             branch: ${{ github.event.pull_request.head.ref }}
             repository: ${{ github.event.pull_request.head.repo.full_name }}
-            os: ${{ matrix.os }}
-            python-version: ${{ matrix.python-version }}
+            os: ${{ vars.DEFAULT_RUNNER }}
+            python-version: ${{ vars.DEFAULT_PYTHON_VERSION }}
         secrets: inherit
 
     # This job does nothing and is only used for branch protection
diff --git a/.github/workflows/scheduled-tests.yml b/.github/workflows/scheduled-tests.yml
index f049f4e40..4746f3e34 100644
--- a/.github/workflows/scheduled-tests.yml
+++ b/.github/workflows/scheduled-tests.yml
@@ -22,7 +22,7 @@ jobs:
                 -   "dbt-snowflake"
                 -   "dbt-spark"
                 os: [ubuntu-22.04, macos-14, windows-2022]
-                python-version: ["3.9", "3.10", "3.11", "3.12"]
+                python-version: ${{ fromJson(vars.SUPPORTED_PYTHON_VERSIONS) }}
         with:
             package: ${{ matrix.package }}
             branch: ${{ github.event.pull_request.head.ref }}
@@ -45,7 +45,7 @@ jobs:
                 -   "dbt-snowflake"
                 -   "dbt-spark"
                 os: [ubuntu-22.04, macos-14, windows-2022]
-                python-version: ["3.9", "3.10", "3.11", "3.12"]
+                python-version: ${{ fromJson(vars.SUPPORTED_PYTHON_VERSIONS) }}
         with:
             package: ${{ matrix.package }}
             branch: ${{ github.event.pull_request.head.ref }}
@@ -66,14 +66,12 @@ jobs:
                 -   "dbt-redshift"
                 -   "dbt-snowflake"
                 -   "dbt-spark"
-                os: [ubuntu-22.04]
-                python-version: ["3.9", "3.10", "3.11", "3.12"]
         with:
             package: ${{ matrix.package }}
             branch: ${{ github.event.pull_request.head.ref }}
             repository: ${{ github.event.pull_request.head.repo.full_name }}
-            os: ${{ matrix.os }}
-            python-version: ${{ matrix.python-version }}
+            os: ${{ vars.DEFAULT_RUNNER }}
+            python-version: ${{ vars.DEFAULT_PYTHON_VERSION }}
         secrets: inherit
 
     notification: