Experiment to find your best mass building exercises

I used to perform lots of squats, and I became incredibly strong with them, going as high as 40 reps with 315 pounds. But there came a point where, even at that level of intensity, my legs weren't growing to my satisfaction. I discovered that my lower back and hips were taking too much of the stress; the solution lay in working my quads more exclusively. I therefore stopped squatting and switched to leg presses and hack squats instead. My legs are now better than ever.