I was training arms with legs and found that my biceps would not grow, because my legs dominated my recovery. Triceps were never a problem, as they are another dominant area for me. Then I moved arms to their own day for a couple months, along with traps, another problem spot. Biceps and traps grew. Now I separate biceps and triceps in push/pull. I have only done this for a couple weeks now, so we will see how it goes. People say I look like I am 10 lbs heavier now, but I am actually the exact same weight, so I would say something is working.