DS (9) is in bed at 7:30 reads for half an hour. When he has Cubs he is in bed at 9:30. Weekends he can stay up as late as he likes. And same for holidays. We are lucky and don't have mood problems the next day. DD is 13 and goes to bed at 9:30 on weeknights and weekends holidays again whenever she likes. They both get up at 6:30 on weekdays and on weekends whenever they like. But usually they are both awake by 9.

I've always let my kids stay up late on occasion to help them to listen to their bodies when it comes to sleep. It's worked well as they often will decide if they have had a big week that they will put themselves early to bed even on the weekends.