Some professionals agree that like all the other muscles in your body, your abs will only be stimulated for growth if you give it recovery time in between your workouts. Your muscles will get bigger when you follow a routine where you workout your abs and then give it time to repair and build, and then repeat the same cycle over again. Accordingly, if you don’t give it a rest, it won’t also have the opportunity to rebuild and grow. The laws of hypertrophy dictate that the break down, repair, and rebuilding of muscles, including the abs, is the best way to go.
Meanwhile, the abs muscles have a relatively unique function that this contention may not always be applicable. The abs forms the bridge between the upper and lower body and helps keep it together. As such, a commonly-held idea is that the abdominals are endurance muscles that are not subject to the laws of hypertrophy. If this is true, then you should be working out your abs as often as you want or everyday for that matter.