Especially in the first couple years of elementary school, I remember many times where the teacher would give us something to do in groups. I get it, the teacher can't be active 7 hours a day as it'd be exhausting. But these two teachers I hated and I think just wanted time to sit on their fat asses.
After that it got a lot better as teachers actually taught and were actively engaged with the class. Even more so in middle school.
In the schools I went to it wasn't sink or swim, but if you didn't get it you simply did what you could and the class moved on. The problem though was if you were able to move at a much faster rate, you couldn't go any faster than the rest of the class. In elementary school I tried convincing my dad to have me skip one or two grades, but he wouldn't go for it.
College I think was the worst, as the focus on memorization and regurgitation was highest. I'd spend endless hours doing rote memorization in the library for exams. The one good thing was learning a skill, which I use for my livelihood. But that was more of a conscious choice than something I would have learned if I took the minimum.