You can perform chest exercises up to 3 non-consecutive days a week. However, if you're lifting heavy weights (enough that you can only complete 6 to 8 repetitions) you'll need at least 2-3 days of rest before you perform the exercises again. For this reason, you may only work your chest once or twice a week. If you're goal is to tone your muscles, you'll want to stick with one to three sets of 12-16 repetitions and at least one day of rest before you perform the exercises again.