I think some schools are adopting new models, but when I graduated from high school <10 years ago, all but a handful of classes were two semesters long (i.e., a

I think some schools are adopting new models, but when I graduated from high school <10 years ago, all but a handful of classes were two semesters long (i.e., autumn and spring would be the same class) and all classes met 5 days a week for approximately an hour, with 7 classes a day. With 180 days of school, with most classes meeting every day of that (save exam time), that is over a thousand hours spent per class.