Exactly. Imagine how painful it would be to read a story that named literally every student and staff member in a 1000 student school. Even just naming all 35 students in one class and house would be ugly and result in constantly wondering “who is so-and-so again?” You have to limit named characters in a story to what…

Rowling, by her own admission, made numerous mistakes in the number of students and lessons of Hogwarts, as well as the number of witches and wizards in Britain, in general. She just picked numbers that sounded good in her head without actually going through the math of how they actually fit together.

Not really, I do adult education and when you’re planning out a schedule, you can easily have 7 to 9 “groups” - especially if you’re doing a block schedule. Nothing says the teachers are teaching every group/level every day.

Is that what it meant? I’d always assumed a “double” class just meant that it was like twice as long as a normal class...

I am more impressed that the houses end up being relatively equal. the sorting hat must do some fudging to even out the classes every once in a while.