In order to gain muscle, you should practice one muscle group at a time, which is mainly divided into chest muscles, back muscles, legs, shoulders and arms (biceps and triceps). According to personal preference, but generally after shoulder exercises, do not practice chest the next day, because chest muscles also need shoulder muscles to stabilize their movements. There are no triceps in front of the chest muscles and biceps in front of the back muscles, because they will affect each other. If every muscle group practices, I personally suggest Monday's shoulders, Tuesday's legs, Wednesday's chest, Thursday's back and Friday's arms.