Intensity is probably one of the missing links in most programs. I can think back to high school and even college and notice how we made tremendous progress because our intensity level was high. I would not say that we had the best program design or the most injury proof exercises. The basic factor of intensity caused us to push our limits to lift heavier or longer, which allowed for muscular adaptations. It helped us to get stronger and bigger.
I can't tell you how many times I work out at commercial gyms where I see the same routines being done with little or no effort. But we also want to see tremendous gains. Is that crazy or not? It takes new amounts of muscular contraction to get new amounts of muscular growth. If you are lifting the same weight, for the same amount of reps, at the same speed I am going to guarantee you that your progress will be stalled. Next time you are in the gym do less talking and push yourselves. You will thank yourself for it.