I used to train very high intensity, 4-6 reps to failure when I was natural, focusing on a lot of strength and it helped me, I just responded well to the lower rep range. Now I have changed it a bit, what I do is warm up with 2-3 sets, working my way up to my heavy set. Then I perform one heavy set of 4-6 reps (only for first exercise of the routine). So for chest I would start with a power movement like incline bench or decline bench, ect. Then stick to 8-10 rep range for rest of sets, and maybe throw in a 15-20 rep set depending on exercise.