When you hear a lot of pros talk, they seem to suggest they get into the gym and make it up as they go along; deciding that today they're going to excessive drop sets, and change everything around. They talk about this being the best way to train, to avoid the body getting used to your program. Especially old school bodybuilders like Arny, who constantly talked about "Shocking the muscle".
Whenever anyone else trains however, they're told that they should pick one program, and stick to it rigorously, only increasing weight along the very strict protocol that the program has set out.
I'm not suggesting that this is wrong, it actually makes a lot of sense, but why is there this discrepancy?