When I was at school and that is not USA but Poland. We used to have 6-8 different subjects per day from biology, chemistry, geography, maths and history as examples. Everyone of this subjects converted to at least an hour of homework. What I learned as a kid is that it is impossible to learn all this things at home and I have to filter what is needed the most. Sometimes approximate and sometimes simply take the risk and just read rapidly the book and count on luck. This what most valuable lesson if learned at school. Some of the kids managed to do this 8 hour drill some like me had to adjust and focus on important stuff learn to filter. This gave me ability to play games and program.