"Every Monday 09:00" is wall-clock time in a zone. "Monday's shift" is an instant. Store one as the other and you get it wrong twice a year.
We keep the pattern naive, put the zone on the plan, and materialise instants per day, which lets the shift crossing the gap really be an hour shorter. Worth checking how your roster handles that.
https://shipmindlabs.com/c/483916ff