There's a lot of good information in this thread, and I don't necessarily disagree with anything that's been said, but just thought I'd throw in my 2 cents. It's true that everyone is composed of differing proportions of different muscle fiber types, and with that said to maximize growth one must stimulate each and every type of muscle fiber with a wide array of weights and rep ranges. As a side note, in my experience training with moderate weight logically is the best way to go (GENERALLY THINKING). Think of it as a numbers game; I can squat 455 x 3 = 1365 lbs, or I can squat 225 x 30 = 6750 lbs, or I can squat 315 x 20 = 6300 lbs! That's almost 5 times as much weight that I've squatted using a lighter weight and higher rep range, but with that said remember that to fully stimulate the muscle one needs to use light, heavy, and moderate weights. Personally, I like to slowly work my way up to my working weight using low reps as to warm, but not pre-fatigue the muscle, then go heavy with my strongest compound movements, then work with moderate weights and finish with lighter weight to maximize the pump.