timo Thank you so much for your quick and helpful reply. I am now using a new weekly tag and it works well. I manually captured the overtime from the previous phase and added it to the new tag, so I'm all set in this regard.
The only disadvantage is that with "weekly", the time sheet starts with a big minus at the beginning of the week, even if you work overtime on day 1. Psychologically, that's not ideal ;-) also, it is only possible to see at the end of the week if you're on track. Thus, for me, the "daily" tag would be better as it allows to have an overview over the working time at the end of each day. However, using "daily" does not seem to be an option for me because I have different standard working hours on different days. If you see a way to capture different daily schedules while allowing a daily overview of whether you're on track with the time, I'd be happy about a hint. Many thanks.