Some of the routines I've had have multiple muscles in the same day. For example: Day 1 has Chest, Back, Biceps and Shoulders while Day 3 has Triceps, Legs, Chest and Shoulders
I'm currently trying to improve and gain mass. I'm 68kg, 175cm and I've been working out for almost two years.
Maybe it's just my opinion, but don't the routines have to focus on max 2 muscles? For example Day 1 would be Biceps and Chest? Since I'm trying to stimulate those specific parts to make them stronger and increase (or make them bigger)
And coming to that, is there some way to do this in a optimal order? For example is it more recommended to work biceps and triceps together rather than biceps with chest?