would like to know if i should use heavy wts all the time threw this program. i see it has you doing 15 and 20 reps to start on some of the exercises isnt that a cutting process not a mass building process, or is that a warm up set the go to the heavy wts after. I started with the beginner and did the itermediate and advanced an have seen improvement just want to make sure Im doing this one right because i want to get big and I have kind of slowed down at this point on my growth