When I think back over my middle-school and high school years, I remember homework as something that bored me to tears and didn't do anything to prepare me for a professional career. There are three things from that period in my life that were far more important, and which wouldn't have been possible if I had to do 3-4 hours of homework every day:
1. Casual reading (anything, really -- except what was assigned to me at school)
2. Working an after-school job
3. Watching contractors at work on construction sites near where I lived, and during the summers when the family was on vacation