It's a complex sport that requires 11 kids to do their job properly. Even with three weekly practices, it's rough.

It's also not static. Changes are made, too. If a kid isn't there for practice, the kid can't play on gameday.

Also, I remember when I thought football required a lot.
That was back before I had a daughter who does comp cheer.
She does about 12 hours of practice per week and the session is more than 11 months long