@Jakob_WMDE thank you very much. I have a non technical suggestion for something else:

• check the tests every Friday afternoon

while CI tests are not essential, it simplifies work and organization on the weekends if tests run.

PS: I wanted to quantify the problem a bit. This year I got 1775 emails from gerrit and 57 contain the word recheck. As most of the logs are gone, it is pointless to analyze this further. My feeling is that in 50% of the cases recheck solved the problem and in the other 50% there was a problem in the ci pipeline. (Not everything was caused by wikibase tests.)

For testing: fork the wikibase repo to your personal GitHub account and modify GH actions there. Possibly use https://github.com/nektos/act to test locally.