What IS needed are a list of guidelines, ability to test an individuals response, variability and UNDERSTANDING that can be applied to a person as an individual that are less specific. What we do know are physiological reactions to exercise, signs of them being optimized, and signs of this optimzation leveling off. To make the best workout, the keyword is always CHANGE the variables to impose a harsh environment the muscles are operating in - without OVERTRAINING or undertraining. There are probably 20 or so variables that can be adjusted in any way (long reps, slow reps, X number of reps, Y number of reps, exercise rest interval, set rest interval, exercises performed, sets performed, exercises, workout order, sequence of exercises, hand placement, workout volume, weight used, etc etc) Again, one size fits all (aka Doggcrap training) methodology that can be viewed on the internet will work well but not optimally for everyone, and not optimally permanently.