I allow my kids to come in up to 90 minutes before school, during the school year, just to work technique and drill- no heavy cardio. Also, no cutting weight.
Mind you, I'm not spitting out NCAA Champions, but the kids love it. Typically no Mondays, unless in-season and we have a tournament the previous weekend. No coaching by me, either, I just unlock. Upperclassmen are expected to lead. If no upperclassmen tell me the day before they'll be going, then I don't unlock.