Depends on how intensely you train them.
Personally, I only see progress if I train a muscle group or a particular exercise twice a week. If I squat, deadlift, or bench only once a weak, I wont make any progress strength wise. If I give a full six days off to any muscle group, I wont see much development.
I train with moderate intensity, could go a lot harder. I've been told that the volume I do is out of whack though so IDK.