this really depends on your goals. i started off doing three days a week which was great for building endurance, but i'd rather be strong. so i cut it down to two days with much harder workouts, plus usually just one sprint day. i need the extra time to recover. so figure out what you want. do you want to be able to do drop and do 50 pushups, or would rather be able to do 5 with a car parked on your back? you can certainly do both, but in that case i would recommend dropping a day and marking the work harder so you're getting strong.