3 or 4 times a wk. would be to much but def.2 times would be ok and you shouldn't be able to train a body part that often if you are totally exausting it. Just because it is not sore doesn't mean you didn't stimulate it.When you are on gear and have been training for a while you probably will not get much soreness if any at all. If you feel like you are not stimulating the muscle enough try going heavier if you can and do some forced reps.