If you train a muscle too hard and too much you’ll over train and not see results. Likewise if you don’t train a muscle enough or hard enough you’ll undertrain and won’t see results. If you do short workout that’s aren’t super intense, like under 10 minutes, you can do that everyday. If your workouts are longer 30-45min at moderate intensity you can do that 3x per week. If your workouts are really hard and your using heavier weights then 2x per week may be all your body can handle. You also want to change your intensity every 2 weeks: 2 weeks of high intensity followed by 2 weeks of low intensity. At www.30DayButtTrainsformation.com we go over all this for you.