ADDED: I often think I couldn't handle high school today.
I'd quit a job as soon as I could find another, if it demanded of me what high school did. Hell, I'd quit based on the consistent 10+ hour days and constant due-tomorrow deadlines, let alone the rest of it like the before-the-sun's-up start time, having to ask permission to go take a piss, sitting in crappy chairs in bad lighting for back-to-back ~hour blocks all day, and having to keep "working" indefinitely with people who won't stop being shitheads in ways that'd get them fired from most any job inside a week. It's insanely terrible.
Like, there are multiple bad things about it that I've never had to tolerate in such abundance and variety even in low-skilled jobs I've held. WTF.
College and adult life are so much more chill than high school. It was a real shock, leaving there for the wider world. So glad the people who were like "this [shitty thing] is to prepare you for the real world, which is way harder and less forgiving!" or "enjoy it, because this is the best time of your life" were entirely wrong. I'd probably have offed myself by now, if they'd been right. Four years was barely tolerable—a lifetime of that, or worse? No, thanks.
Everything else is much worse for how I think. I don't get to choose how to time my schedule, the curriculum is mostly fixed (you would always have math/english/history, some language for 3/4 years. You only choose an elective and maybe 1 year of science) and homework tended to stack up constantly because every class was 1 hour M-F. And yea, as you mentioned it's absurd having 1 day due homework spring up when you may or may not be preparing for some other project, or test, or even competition.
You also were much more pressured against taking time to yourself. You can skip a class or take a sick day in "the real world" if you need a break or emergencies come up. those "perfect attendence" rewards were the worst grift of the education system.