In order to grow, you must train with a certain amount of volume. Most research does not explore the effects of using more than three sets on hypertrophy, and the data that does exist does not consistently show the benefits of using more than three sets.
Forty-eight untrained men were randomly assigned to one of the three training groups: one set, three sets, five sets, or a control group. Subjects completed a full-body workout each session. All training groups performed three resistance-training sessions per week for six months.
The one-set group did not show a significant change in biceps or triceps thickness after six months of training. The three-sets group did see a significant increase in muscle thickness but only for biceps. The five-sets group saw a significant increase in muscle thickness for both biceps and triceps, and that difference was significantly greater than both groups.
Doing 15 sets per muscle group spread out over three workouts per week will provide faster gains than fewer sets per week.
One way to apply these findings is to do full-body workouts three times per week. You would then do five sets for each muscle group each workout. Another way would be to split the body into either “push/pull” or “upper/ lower” muscle groups and train four to six times per week.