diff --git a/.github/workflows/checks-integration.yml b/.github/workflows/checks-integration.yml
index 205599a4aa3..4b4f7ff2d09 100644
--- a/.github/workflows/checks-integration.yml
+++ b/.github/workflows/checks-integration.yml
@@ -7,6 +7,7 @@ on:
   schedule:
     - cron: '0 23 * * SUN-THU'
   workflow_dispatch:
+  pull_request: {}
 
 concurrency:
   group: ${{ github.workflow }}-${{ github.ref == 'refs/heads/master' && github.run_number || github.ref }}
@@ -14,7 +15,7 @@ concurrency:
 
 jobs:
   checks:
-    if: (github.event_name == 'schedule' && github.repository == 'optuna/optuna') || (github.event_name != 'schedule')
+    # if: (github.event_name == 'schedule' && github.repository == 'optuna/optuna') || (github.event_name != 'schedule')
     runs-on: ubuntu-latest
 
     steps:
diff --git a/.github/workflows/checks.yml b/.github/workflows/checks.yml
index 899793c7342..51011eb0d91 100644
--- a/.github/workflows/checks.yml
+++ b/.github/workflows/checks.yml
@@ -14,7 +14,7 @@ concurrency:
 
 jobs:
   checks:
-    if: (github.event_name == 'schedule' && github.repository == 'optuna/optuna') || (github.event_name != 'schedule')
+    # if: (github.event_name == 'schedule' && github.repository == 'optuna/optuna') || (github.event_name != 'schedule')
     runs-on: ubuntu-latest
 
     steps:
diff --git a/.github/workflows/mac-tests.yml b/.github/workflows/mac-tests.yml
index 249bbf1453d..5dae7aaece0 100644
--- a/.github/workflows/mac-tests.yml
+++ b/.github/workflows/mac-tests.yml
@@ -62,13 +62,13 @@ jobs:
 
 
     - name: Scheduled tests
-      if:  ${{ github.event_name == 'schedule' || github.event_name == 'workflow_dispatch' }}
+      # if:  ${{ github.event_name == 'schedule' || github.event_name == 'workflow_dispatch' }}
       run: |
         pytest tests -m "not integration"
-    - name: Tests
-      if:  ${{ github.event_name != 'schedule' && github.event_name != 'workflow_dispatch' }}
-      run: |
-        pytest tests -m "not integration and not slow"
+    # - name: Tests
+    #   if:  ${{ github.event_name != 'schedule' && github.event_name != 'workflow_dispatch' }}
+    #   run: |
+    #     pytest tests -m "not integration and not slow"
 
 
   tests-integration-mac:
diff --git a/.github/workflows/tests-integration.yml b/.github/workflows/tests-integration.yml
index fe52c51b588..31a7e68e847 100644
--- a/.github/workflows/tests-integration.yml
+++ b/.github/workflows/tests-integration.yml
@@ -15,19 +15,19 @@ concurrency:
 
 jobs:
   tests-integration:
-    if: (github.event_name == 'schedule' && github.repository == 'optuna/optuna') || (github.event_name != 'schedule')
+    # if: (github.event_name == 'schedule' && github.repository == 'optuna/optuna') || (github.event_name != 'schedule')
     runs-on: ubuntu-latest
 
     strategy:
       matrix:
         python-version: ['3.8', '3.9', '3.10', '3.11']
-        test-trigger-type:
-          - ${{ (github.event_name == 'schedule' || github.event_name == 'workflow_dispatch') && 'Scheduled' || '' }}
-        exclude:
-          - test-trigger-type: ""
-            python-version: "3.9"
-          - test-trigger-type: ""
-            python-version: "3.10"
+        # test-trigger-type:
+        #   - ${{ (github.event_name == 'schedule' || github.event_name == 'workflow_dispatch') && 'Scheduled' || '' }}
+        # exclude:
+        #   - test-trigger-type: ""
+        #     python-version: "3.9"
+        #   - test-trigger-type: ""
+        #     python-version: "3.10"
 
     steps:
     - name: Checkout
@@ -75,11 +75,11 @@ jobs:
         pipdeptree
 
     - name: Scheduled tests
-      if:  ${{ github.event_name == 'schedule' || github.event_name == 'workflow_dispatch' }}
+      # if:  ${{ github.event_name == 'schedule' || github.event_name == 'workflow_dispatch' }}
       run: |
         pytest tests -m "integration"
 
-    - name: Tests
-      if:  ${{ github.event_name != 'schedule' && github.event_name != 'workflow_dispatch' }}
-      run: |
-        pytest tests -m "integration and not slow"
+    # - name: Tests
+    #   if:  ${{ github.event_name != 'schedule' && github.event_name != 'workflow_dispatch' }}
+    #   run: |
+    #     pytest tests -m "integration and not slow"
diff --git a/.github/workflows/tests-mpi.yml b/.github/workflows/tests-mpi.yml
index ad80ae04d0d..e02115e7851 100644
--- a/.github/workflows/tests-mpi.yml
+++ b/.github/workflows/tests-mpi.yml
@@ -15,19 +15,19 @@ concurrency:
 
 jobs:
   tests-mpi:
-    if: (github.event_name == 'schedule' && github.repository == 'optuna/optuna') || (github.event_name != 'schedule')
+    # if: (github.event_name == 'schedule' && github.repository == 'optuna/optuna') || (github.event_name != 'schedule')
     runs-on: ubuntu-latest
 
     strategy:
       matrix:
         python-version: ['3.8', '3.9', '3.10', '3.11']
-        test-trigger-type:
-          - ${{ (github.event_name == 'schedule' || github.event_name == 'workflow_dispatch') && 'Scheduled' || '' }}
-        exclude:
-          - test-trigger-type: ""
-            python-version: "3.9"
-          - test-trigger-type: ""
-            python-version: "3.10"
+        # test-trigger-type:
+        #   - ${{ (github.event_name == 'schedule' || github.event_name == 'workflow_dispatch') && 'Scheduled' || '' }}
+        # exclude:
+        #   - test-trigger-type: ""
+        #     python-version: "3.9"
+        #   - test-trigger-type: ""
+        #     python-version: "3.10"
 
     steps:
     - name: Checkout
diff --git a/.github/workflows/tests-storage.yml b/.github/workflows/tests-storage.yml
index 397cbf8a37f..3b3cc4f0016 100644
--- a/.github/workflows/tests-storage.yml
+++ b/.github/workflows/tests-storage.yml
@@ -18,21 +18,21 @@ jobs:
   # RDB. Since current name "tests-rdbstorage" is required in the Branch protection rules, you
   # need to modify the Branch protection rules as well.
   tests-rdbstorage:
-    if: (github.event_name == 'schedule' && github.repository == 'optuna/optuna') || (github.event_name != 'schedule')
+    # if: (github.event_name == 'schedule' && github.repository == 'optuna/optuna') || (github.event_name != 'schedule')
     runs-on: ubuntu-latest
 
     strategy:
       matrix:
         python-version: ['3.7', '3.8', '3.9', '3.10', '3.11']
-        test-trigger-type:
-          - ${{ (github.event_name == 'schedule' || github.event_name == 'workflow_dispatch') && 'Scheduled' || '' }}
-        exclude:
-          - test-trigger-type: ""
-            python-version: "3.8"
-          - test-trigger-type: ""
-            python-version: "3.9"
-          - test-trigger-type: ""
-            python-version: "3.10"
+        # test-trigger-type:
+        #   - ${{ (github.event_name == 'schedule' || github.event_name == 'workflow_dispatch') && 'Scheduled' || '' }}
+        # exclude:
+        #   - test-trigger-type: ""
+        #     python-version: "3.8"
+        #   - test-trigger-type: ""
+        #     python-version: "3.9"
+        #   - test-trigger-type: ""
+        #     python-version: "3.10"
 
     services:
       mysql:
diff --git a/.github/workflows/tests-with-minimum-versions.yml b/.github/workflows/tests-with-minimum-versions.yml
index 679d9ef7e66..7594cd6a65c 100644
--- a/.github/workflows/tests-with-minimum-versions.yml
+++ b/.github/workflows/tests-with-minimum-versions.yml
@@ -15,7 +15,7 @@ concurrency:
 
 jobs:
   tests-with-minimum-versions:
-    if: (github.event_name == 'schedule' && github.repository == 'optuna/optuna') || (github.event_name != 'schedule')
+    # if: (github.event_name == 'schedule' && github.repository == 'optuna/optuna') || (github.event_name != 'schedule')
     runs-on: ubuntu-latest
 
     strategy:
@@ -82,11 +82,11 @@ jobs:
         pipdeptree
 
     - name: Scheduled tests
-      if:  ${{ github.event_name == 'schedule' || github.event_name == 'workflow_dispatch' }}
+      # if:  ${{ github.event_name == 'schedule' || github.event_name == 'workflow_dispatch' }}
       run: |
         pytest tests -m "not integration"
 
-    - name: Tests
-      if:  ${{ github.event_name != 'schedule' && github.event_name != 'workflow_dispatch' }}
-      run: |
-        pytest tests -m "not integration and not slow"
+    # - name: Tests
+    #   if:  ${{ github.event_name != 'schedule' && github.event_name != 'workflow_dispatch' }}
+    #   run: |
+    #     pytest tests -m "not integration and not slow"
diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 052430215ed..e38cdfad891 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -15,23 +15,23 @@ concurrency:
 
 jobs:
   tests:
-    if: (github.event_name == 'schedule' && github.repository == 'optuna/optuna') || (github.event_name != 'schedule')
+    # if: (github.event_name == 'schedule' && github.repository == 'optuna/optuna') || (github.event_name != 'schedule')
     runs-on: ubuntu-latest
 
     strategy:
       matrix:
         python-version: ['3.7', '3.8', '3.9', '3.10', '3.11', '3.12']
-        test-trigger-type:
-          - ${{ (github.event_name == 'schedule' || github.event_name == 'workflow_dispatch') && 'Scheduled' || '' }}
-        exclude:
-          - test-trigger-type: ""
-            python-version: "3.8"
-          - test-trigger-type: ""
-            python-version: "3.9"
-          - test-trigger-type: ""
-            python-version: "3.10"
-          - test-trigger-type: ""
-            python-version: "3.11"
+        # test-trigger-type:
+        #   - ${{ (github.event_name == 'schedule' || github.event_name == 'workflow_dispatch') && 'Scheduled' || '' }}
+        # exclude:
+        #   - test-trigger-type: ""
+        #     python-version: "3.8"
+        #   - test-trigger-type: ""
+        #     python-version: "3.9"
+        #   - test-trigger-type: ""
+        #     python-version: "3.10"
+        #   - test-trigger-type: ""
+        #     python-version: "3.11"
 
     services:
       redis:
@@ -87,12 +87,13 @@ jobs:
 
     - name: Tests
       run: |
-        if [ "${{ github.event_name }}" = "schedule" ] || \
-           [ "${{ github.event_name }}" = "workflow_dispatch" ] ; then
-          target="not integration"
-        else
-          target="not integration and not slow"
-        fi
+        # if [ "${{ github.event_name }}" = "schedule" ] || \
+        #    [ "${{ github.event_name }}" = "workflow_dispatch" ] ; then
+        #   target="not integration"
+        # else
+        #   target="not integration and not slow"
+        # fi
+        target="not integration"
 
         if [ "${{ matrix.python-version }}" = "3.12" ] ; then
           # TODO(not522): Remove ignores when BoTorch supports Python 3.12
diff --git a/.github/workflows/windows-tests.yml b/.github/workflows/windows-tests.yml
index e6114f1aa84..599b7bb08eb 100644
--- a/.github/workflows/windows-tests.yml
+++ b/.github/workflows/windows-tests.yml
@@ -21,7 +21,7 @@ jobs:
     runs-on: windows-latest
 
     # Not intended for forks.
-    if: (github.event_name == 'schedule' && github.repository == 'optuna/optuna') || (github.event_name != 'schedule')
+    # if: (github.event_name == 'schedule' && github.repository == 'optuna/optuna') || (github.event_name != 'schedule')
     steps:
     - name: Checkout
       uses: actions/checkout@v3
@@ -63,25 +63,25 @@ jobs:
         pipdeptree
 
     - name: Scheduled tests
-      if:  ${{ github.event_name == 'schedule' || github.event_name == 'workflow_dispatch' }}
+      # if:  ${{ github.event_name == 'schedule' || github.event_name == 'workflow_dispatch' }}
       run: |
         pytest -m "not integration"
       env:
         SQLALCHEMY_WARN_20: 1
         MPLBACKEND: "QtAgg" # Use QtAgg as matplotlib backend.
 
-    - name: Tests
-      if:  ${{ github.event_name != 'schedule' && github.event_name != 'workflow_dispatch' }}
-      run: |
-        pytest -m "not integration and not slow"
-      env:
-        MPLBACKEND: "QtAgg" # Use QtAgg as matplotlib backend.
+    # - name: Tests
+    #   if:  ${{ github.event_name != 'schedule' && github.event_name != 'workflow_dispatch' }}
+    #   run: |
+    #     pytest -m "not integration and not slow"
+    #   env:
+    #     MPLBACKEND: "QtAgg" # Use QtAgg as matplotlib backend.
 
   tests-integration-windows:
     runs-on: windows-latest
 
     # Not intended for forks.
-    if: (github.event_name == 'schedule' && github.repository == 'optuna/optuna') || (github.event_name != 'schedule')
+    # if: (github.event_name == 'schedule' && github.repository == 'optuna/optuna') || (github.event_name != 'schedule')
     steps:
     - name: Checkout
       uses: actions/checkout@v3