to me this is a trick question. there is a relationship between intensity, volume, and frequency. change one and the others must change. to make it more complicated, one recovery ability changes over time so you can handle more of all of them. so any program you are on unless it builds in progression taking into account increased workout capacity and increased strength output cannot be optimal.
one could also add in the idea of beliefs. after training people for years i noticed that if someone did not believe in the program they would half ass it and therefore get sub optimal results. it was not the training but the trainee that was sub optimal.
throw in nutrition and sleep patterns and we get an entire new set of complications. as in you may have a great program, and a trainee that puts in the work but they sleep like crap and eat like crap. they can and may see some gains for some time but they will not be optimal.
there is even a fringe idea that even if what you do seems optimal, is it? you dont really know without trying something else. and how long do you try it out? did the previous program hurt or help you?
now it is not so daunting as i make it sound. IMO as long as you see results, and you are happy with those results, and can maintain those results and the progress then you are optimal enough.
as for what i have done that has helped for whatever goals i may have had over the years, well it was whatever i did consistently and intensely with enough sleep and food.
i will have to say my current goals are to compete in powerlifting and IMO my gains in the year since i started that training have been greater then any other training, besides my high school sports and i had a coach for that. i currently follow the westside template. i would love to say its the conjugate method but i wonder if the russian ideal of the conjugate method is what westside really does. but we can save that for another day. either way i am hardly changing my lifts and still progressing quite well IMO.
to further my thoughts on the westside template it is just that, a template. you have 2 DE days (1 upper and 1 lower), 2 ME days (1 upper and 1 lower), and 4 RE days (2 upper and 2 lower). i have recently been doing extra work adding in plyo/reactive work. i do lower body on upper body days and upper on lower body days. so one can say i am doing full body work 4 days a week. to me that is the beauty of westside. i have recently been relating it to the jeet kune do of lifting. i still believe conjugate would be even more accurate to that analogy. i am separating conjugate from westside based upon views from professor verkhoshansky. i am big believer of his views and he states westside is not conjugate. now i will admit i would love to find out more before i finalize an opinion, but for now i see similarities and am undecided which way to sway.