Currently, I have to go into the settings every Friday and change the end time to 2p, then go back in on Sunday to change it back to 6a
You can start charging outside the schedule by pressing the 'hold' button inside the charging door.
It's not a great solution but, you might be able to just leave the schedule at 12 - 6 and manually start charging when needed between 6 am and 2 pm on the weekends. Although, you might also need to remember to manually stop charging at 2 pm. So, my 'solution' might end up being just as annoying as changing your schedule every Friday and Sunday.
Update
I tried to reproduce the scenario I suggested above. My charging schedule ends at 4:00 pm so I plugged in around 3:50 pm and let the car charge. Then, around 6:15 pm I went back to the car to try starting an 'override' charging session.
A problem I ran into was that the SoC indicator and the two buttons inside the charging door were not illuminated. Pressing the 'Hold' button had no effect whatsoever.
I tried unlocking and then locking the car - that also had no effect.
Then I disconnected and reconnected the charging cable. At that point the SoC indicator and the two buttons lit up. Then I pressed the 'Hold' button and the car started charging. So, the scenario does work, but it is even more fiddly than I thought.