I like training with full body workouts. I workout on days when my body and mind feels fresh and ready. Sometimes I only need two days rest, sometimes six days, etc.
I think for me it is best to listen to my body on when how often to train, how many sets.
There are so many factors that affect recovery such as how much sleep, what your diet was like, how much stress at work and home, hormonas levels, and that sticking to a cookie cutter program tends to fail after a while due to lack of recovery, lack of motivation or boredom.
Not everyone can recover at the same rate so why do so many different people try to do the same programs.
Specific programs might be good for peaking for powerlifting comps and other athletic endeavors, or to use over the short term to bust through plateaus.