I really don’t believe there is one best training schedule. No matter how much you think you’ve designed the best system, your body will prove you wrong.
It always figures it out and then you start to go stale so you have to change.
However, the system I have used the longest and seem to get the most results from is to split the body into 39 muscle groups then work 20 each day for 3 days to get through the entire body.
How come the numbers don’t add up? Because I like to work all 9 abdominal muscles and one aerobic exercise each day.