I completely agree, there is no way that your brain can process eight hours of new information a day (on a level of testing comprehension). I have always found that those people who spend that much time in the library are just not studying the correct way. In a lot of my business classes, people would spend hours upon hours trying to memorize details instead of learning to apply the theory and concepts in 2-3 hours. Don't get me wrong, in reviewing for an exam/final, I could spend an eight hour day going back over notes, but that is not processing new information or an upkeep scenario.
As for the MCAT, I'm putting in 1-2 hours a day, 5-6 days a week. Since I don't watch TV, this is quite easy.
Adam