One pet peeve I have always had is that everybody responds differently to certain ways of training. It's extremely annoying because you can spend decades trying different methods to figure out what works for you and you still may not know what works 100% for you. With dieting it makes sense that some people can take in more carbs than others due to insulin resistance and sensitivity. It also makes sense that your body type can affect your metabolism which can also impact how you diet so I understand how dieting can be different but when it comes to actually pure muscle building I don't see how there isn't a scientific method proving what type of training will cause ultimate muscle growth. You have people like Ben Pakulski who's approach is everything by science. Apparently he states that 8reps is the exact number for the maximum amount of muscle building and 40 to 60 seconds rest is the exact amount of time between sets for muscle building. But he also gets a lot of crap for incorrect information. Then you have articles saying that hypertrophy is the only true way to build muscle. I believe the article on hypertrophy I read was 8 to 12 reps with 60 to 90 seconds rest if I recall correctly. But then I asked myself what about heavy strength training? Resting 4 to 5 minutes in between sets will allow you to lift more weight than you ever could have with shorter rest periods. If you are lifting more weight you should build more muscle. The only difference between individuals aside from gear/food intake that would affect muscle building that I can think of is recovery. Your body type could determine this but I still don't see how there isn't a scientific proven method to build muscle so you know what you're doing every day in the gym is building muscle if that is your goal.