One thing that bothers me a lot, and I see it all the time, is when young bodybuilders start to complicate their programs with techniques and philosophy that is far too advanced for them. As a young bodybuilder, you have to realize that the absolute number one way to gain maximum muscle mass in the shortest possible time is to train using progressive overload.
I think what has happened, is that the age of information and internet access has confused people. They see the pros training with lighter weights, or doing complex supersets, and they think they need to do that stuff to grow. The truth is that most really big bodybuilders are already maxed out with many years of training "heavy" with progressive overload. They simply can't keep adding plates to everything or they will be injured constantly. They are training with more volume and dynamic loading, varying rep tempos, shorter rest periods, etc, in an effort to not get hurt using the massive weights they could be using. There does come a point when you can get so strong that you actually become a danger to yourself.
I started training when I was 14 years old, at 138 pounds. I focused on Dorian Yates style progressive overload training (6-10 reps on almost all my working sets) for the vast majority of my time in the gym between 1990 and 2004. By that time, I was 250 lbs on stage, and over 300 lbs off season. It worked. I'd say that in that entire time I used probably the same 20 exercises over and over again, always trying to get stronger. The fact remains that if YOU can add a plate to your 10 rep squat, you WILL have bigger legs. Moving more weight through proper ranges, with good tempo and control, will yield gains. It simply can't be avoided.
Not to be confused with getting stronger on single reps. That's powerlifter stuff, and doesn't yield much growth because the reps are too low. When I say getting stronger, I'm talking about the weights you use for proper "bodybuilder" sets. You have to leave it all on the gym floor. Max effort sets of progressive overload will serve you well.
So keep a journal, set goals, and chase those numbers. One pound at a time, you can guarantee growth by working towards adding a few pounds to your lifts, over and over again. Start with a 6 rep weight, and when you finally get 10 reps, then it's time to add weight next time you do that exercise. Simple.
Train like hell,