I guess I see what you mean - it’s partially our fault. The multi-override feature supports different shifts with the same selection. So you could - theoretically - select 2 blocks with different start and end times and override both - but since the times are different…
Now it is indeed true, we are showing the standard override popup with the time selectors, but the backend can’t really decide to only partially override those shifts - all the blocks should go to the selected person.
I wish I could tell you that we will be improving this in a way that it fits your specific situation - but given the complexity with the different length shifts, I think the function will be working the same way in the future (but indeed, the UI needs an update when multiple shifts are selected)
In your case - to reduce the manual work - you could consider adding a temporary rotation for those times (which can rotate every 6 hour etc), and just override the original blocks with “no-one”. This will result is a final schedule which is matching your requirements and has considerably less steps then adding overrides one by one.
Do you think that would work?