There are always going to be those guys who hang out in the gym, seemingly forever. Every time you go, they are there. But for maximum muscle mass you only need to work out between 45 minutes and an hour each session. Your muscle building (anabolic) and muscle destruction (catabolic) hormones must be kept in the proper balance for your efforts to be successful.
When you focus hard on your exercises for 45 to 60 minutes, you keep your anabolic hormones high and your catabolic hormones low. This is the “sweet spot” for muscle mass development. And quite frankly, if it takes you more than 60 minutes to work out, you are probably not working hard enough. Push yourself through focused muscle building workouts of 60 minutes or less, and you will find yourself building more muscle mass per hour than those gym rats who never seem to go home.