USA: Typically for us, about 7-ish hours, I have to go in the building before classes start before then though, making it about 8 hours. Sometimes, we have half days, but they’re pretty rare. We have all our classes, they’re just very condensed 4-5 hours.
Here, we start at like 07:00 (Mondays 08:10 or so) and we end at 14:50.
Norway: 6-7 hours apparently, from 08:00-14:00 (2: p.m.) or 15:00. (3 p.m.)
It could be shorter, but not by much: the school restaurant is a 10-minute walk from the school, and of course being French the food is ultra-local, organic, in-season home-cooked three-course meals (plus the cheese course, obviously), which you don’t scarf down).
Still, it’s annoying. My kid is very young still and 6 is very late for her.