I do chest bicep, and back tricep. But on days I'm doing chest with bicep or back with tricep. Ill only do 2 exercises for bicep and tricep. Just to say they are stimulated. But then on friday I do an arm day bicep and tricep. Where my focus is on arms and I do more exercises. So 1 day its just 2 exercises for stimulation. Then on the arm day is when I go heavy and really go at it.