Alot of individuals believe in taking days off training.
I don't believe in this practice personally. The fact that you are training 1 or 2 seperate body parts only daily, puts more than adequate recovery time for muscles trained.
Say you trained chest and tri's, the next day back and bi's, then shoulders, then finally legs. That makes 4 days recovery time for said muscles trained. Thats almost too much time resting muscles in between. If you added a couple of rest days, your in between time becomes SIX whole days in between. You need to hit it more often than that for optimal growth. Days off are an EXCUSE to be LAZY. WORK EVERY FUCKING DAY, and add in abs and forearms to one of your existing training days. NO DAYS OFF!
This is merely my ways and opinions. I am not an authority on this. Let me know your ways and thoughts on working out and time off.