I think the main problem with high school is that it wastes an absolute shitload of time. About 8 hours of your day shot actually in school, most of which is extremely low value or idle, and then (in my case, at what I think was a pretty middle-of-the-road school) 60+ minutes of homework on top of that every single day, which you're to do after you're already mentally beat from the intense boredom and "pay attention at all times or get in trouble" atmosphere of the rest of the day, with no option to defer it until you don't feel quite as much like your brain is running out through your ears.

As a staunch advocate of teaching the humanities and someone who thinks the "what k-12 education needs is math education that looks more like what the 0.1% of people who are math nerds wish they'd been taught" folks are dead wrong, I still think high schools ought to re-consider having every class be the same length, and maybe cut some of their social studies and history entirely (because it's almost never well-taught enough to be worthwhile) so the homework portion of mid- and high-level math classes can be brought into the school day proper. It'd be a much better use of time, and I think having a teacher available for questions and guidance during "homework" time would do wonders for math comprehension and test scores.

Though how schools would justify giving their coaches full teacher salaries without as many history and social studies classes for them to teach, is an open question.

Since high school, no one has stopped me to check if I was wearing panties before going into a work-sanctioned party.

But at my high school, they did.