diff --git a/.github/workflows/test_eessi.yml b/.github/workflows/test-pilot.nessi.no.yml
similarity index 62%
rename from .github/workflows/test_eessi.yml
rename to .github/workflows/test-pilot.nessi.no.yml
index fee95f6b79..6342d5df19 100644
--- a/.github/workflows/test_eessi.yml
+++ b/.github/workflows/test-pilot.nessi.no.yml
@@ -1,80 +1,66 @@
 # documentation: https://help.github.com/en/articles/workflow-syntax-for-github-actions
-name: Tests relying on having EESSI pilot repo mounted
+name: Check for missing software installations in pilot.nessi.no
 on: [push, pull_request, workflow_dispatch]
 permissions:
   contents: read # to fetch code (actions/checkout)
 jobs:
-  pilot:
-    runs-on: ubuntu-20.04
+  check_missing:
+    runs-on: ubuntu-22.04
     strategy:
       fail-fast: false
       matrix:
         EESSI_VERSION:
         - 2023.06
-        EESSI_SOFTWARE_SUBDIR:
+        EESSI_SOFTWARE_SUBDIR_OVERRIDE:
 #        - aarch64/generic
         - x86_64/amd/zen2
         - x86_64/intel/broadwell
-#        - x86_64/intel/cascadelake
         - x86_64/intel/skylake_avx512
         - x86_64/generic
-        EASYSTACK_FILE:
-        - eessi-2023.06-eb-4.7.2-2021a.yml
-        - eessi-2023.06-eb-4.7.2-2021b.yml
-        - eessi-2023.06-eb-4.7.2-2022a.yml
-        - eessi-2023.06-eb-4.7.2-2022b.yml
-        - eessi-2023.06-eb-4.7.2-system.yml
-        - eessi-2023.06-eb-4.8.0-system.yml
-        - eessi-2023.06-eb-4.8.1-2022a.yml
-        - eessi-2023.06-eb-4.8.1-system.yml
-        - eessi-2023.06-eb-4.8.2-2022a.yml
     steps:
         - name: Check out software-layer repository
           uses: actions/checkout@93ea575cb5d8a053eaa0ac8fa3b40d7e05a33cc8 # v3.1.0
 
-        - name: Mount EESSI CernVM-FS pilot repository
+        - name: Mount NESSI CernVM-FS repository
           uses: cvmfs-contrib/github-action-cvmfs@d4641d0d591c9a5c3be23835ced2fb648b44c04b # v3.1
           with:
               cvmfs_config_package: https://github.com/NorESSI/filesystem-layer/releases/download/latest/cvmfs-config-nessi_latest_all.deb
               cvmfs_http_proxy: DIRECT
               cvmfs_repositories: pilot.nessi.no
 
-        - name: Test check_missing_installations.sh script with EESSI_SOFTWARE_SUBDIR_OVERRIDE
-          if: '!cancelled()'
-          run: |
-              export EESSI_SOFTWARE_SUBDIR_OVERRIDE=${{matrix.EESSI_SOFTWARE_SUBDIR}}
-              source /cvmfs/pilot.nessi.no/versions/${{matrix.EESSI_VERSION}}/init/bash
-              module load EasyBuild
-              eb --version
-              export EESSI_PREFIX=/cvmfs/pilot.nessi.no/versions/${{matrix.EESSI_VERSION}}
-              export EESSI_OS_TYPE=linux
-              env | grep ^EESSI | sort
-              echo "just run check_missing_installations.sh (should use ${{matrix.EASYSTACK_FILE}})"
-              ./check_missing_installations.sh ${{matrix.EASYSTACK_FILE}}
-
-        - name: Test check_missing_installations.sh script without EESSI_SOFTWARE_SUBDIR_OVERRIDE
-          if: '!cancelled()'
+        - name: Test check_missing_installations.sh script
           run: |
+              export EESSI_SOFTWARE_SUBDIR_OVERRIDE=${{matrix.EESSI_SOFTWARE_SUBDIR_OVERRIDE}}
               source /cvmfs/pilot.nessi.no/versions/${{matrix.EESSI_VERSION}}/init/bash
+              # set $EESSI_CPU_FAMILY to the CPU architecture that corresponds to $EESSI_SOFTWARE_SUBDIR_OVERRIDE (part before the first slash),
+              # to prevent issues with checks in the Easybuild configuration that use this variable
+              export EESSI_CPU_FAMILY=${EESSI_SOFTWARE_SUBDIR_OVERRIDE%%/*}
               module load EasyBuild
+              which eb
               eb --version
               export EESSI_PREFIX=/cvmfs/pilot.nessi.no/versions/${{matrix.EESSI_VERSION}}
               export EESSI_OS_TYPE=linux
-              export EESSI_SOFTWARE_SUBDIR=${{matrix.EESSI_SOFTWARE_SUBDIR}}
               env | grep ^EESSI | sort
-              echo "just run check_missing_installations.sh (should use ${{matrix.EASYSTACK_FILE}})"
-              ./check_missing_installations.sh ${{matrix.EASYSTACK_FILE}}
+              echo "just run check_missing_installations.sh (should use easystacks/pilot.nessi.no/${{matrix.EESSI_VERSION}}/eessi-${{matrix.EESSI_VERSION}}-*.yml)"
+              for easystack_file in $(ls easystacks/pilot.nessi.no/${{matrix.EESSI_VERSION}}/eessi-${{matrix.EESSI_VERSION}}-eb-*.yml); do
+                  echo "check missing installations for ${easystack_file}..."
+                  ./check_missing_installations.sh ${easystack_file}
+                  ec=$?
+                  if [[ ${ec} -ne 0 ]]; then echo "missing installations found for ${easystack_file}!" >&2; exit ${ec}; fi
+              done
 
         - name: Test check_missing_installations.sh with missing package (GCC/8.3.0)
-          if: '!cancelled()'
           run: |
+              export EESSI_SOFTWARE_SUBDIR_OVERRIDE=${{matrix.EESSI_SOFTWARE_SUBDIR_OVERRIDE}}
               source /cvmfs/pilot.nessi.no/versions/${{matrix.EESSI_VERSION}}/init/bash
+              # set $EESSI_CPU_FAMILY to the CPU architecture that corresponds to $EESSI_SOFTWARE_SUBDIR_OVERRIDE (part before the first slash),
+              # to prevent issues with checks in the Easybuild configuration that use this variable
+              export EESSI_CPU_FAMILY=${EESSI_SOFTWARE_SUBDIR_OVERRIDE%%/*}
               module load EasyBuild
               which eb
               eb --version
               export EESSI_PREFIX=/cvmfs/pilot.nessi.no/versions/${{matrix.EESSI_VERSION}}
               export EESSI_OS_TYPE=linux
-              export EESSI_SOFTWARE_SUBDIR=${{matrix.EESSI_SOFTWARE_SUBDIR}}
               env | grep ^EESSI | sort
               # create dummy easystack file with a single entry (something that is not installed in EESSI)
               easystack_file="test.yml"