If you put in the right INTENSITY…and I’m not talking about reps/sets/volume, or any other variable I’m talking about the intensity you put into it, the feel of the muscle…then working a muscle group every 3-5 days should be about right. I think once a week isn’t going to do it because either a) you’ll end up putting in so much volume during that one workout that you’ll breakdown too much an unable to adapt and supercompensate or b) you’ll put in the right intensity or less intensity but either way you’ve got fucking 7 days before you hit that muscle again…far too long. You also have to pay attention to cross-over…every time you work chest you’re also working tri’s and shoulders (anterior), every time you work back you’re also working bi’s and shoulders (posterior). So include shoulders and arms in your program, but you may not need to hit them as often as the others.
I’d say experiment, that’s how I learned what’s best for me right now and that’s how everyone else on the planet has learned as there isn’t best optimal approach for every person in every situation.
This has worked well for me:
Monday: Chest/Back A
Tuesday: Legs (Squat emphasis)
Thursday: Chest/Back B
Friday: Legs (Deadlift emphasis)
Most workouts are 45-60 minutes long, rarely more than 60s rest between anything except leg day. I don’t time rest, I just go by feel. Saturday is a bit longer, at least 60 minutes. I went from 143 to 164 in 6 months.