there are three types of muscle fiber in the fast twitch group, and each benefits at a different rep range
I may have this backwards, but you get the idea
fiber type / best rep range
1 - 5 reps
2 - 10 reps
3 - 15 reps
I usually do pyramids working up and down the rep range. the problem for me, with the heavier weigghts, is that it takes a toll on tendons. I can compensate by taking TB500, but even then, I've been avoiding the heavier weight that takes me in the 5 rep to failure range. Young bulls have an easier time with the heavier weights on their tendons............