That's really all I can say. I agree with this so much. (Wow, I'm articulate!) I just wish it were easier to do.
Personal story: I'm in high school right now. Many of the courses I'm taking are very... high-school-y. Low on content and high on busy-work and hand-waving. Some, though, I find are actually well taught; namely, my Statistics course and my Multivariable Calculus/DiffEq course. The teacher for the Stat course posted all the homework he plans to assign (all out of the book) online; while the teacher for Multivariable hasn't done that, he assigns the same homework every year, so I managed to get his homework from previous students. Currently, I'm done with my statistics course and 3/4 through the multivariable course, where both of them should be full-year courses. It just feels amazing to be learning at my own pace - the class speed in high school (and, I guess, college, and perhaps life) is catering to the lowest denominator. I know that I, and many of my classmates, could easily double or in some cases triple that speed.