There are usually a number of different approaches that will work for anyone, once they've been discovered. Most don't try enough alternatives to find out which ones, therefore assume that only one approach works. A little experimentation's a huge advantage. Another good approach is to tailor slight variations into existing programs, to see which works best.
The other factor is motivation-if two approaches work but one is much more appealing to do long-term, that's the one to use. The only caveat: there may be other approaches out there that are equally appealing that haven't yet been tried.
Volume as an example: moderate sets with more effective use of each set using higher intensity can be as or more effective, while still being similar enough to appeal to volume trainers. Some who've used volume might appreciate moderate volume even more because there's more intensity & workouts aren't as drawn-out. From experience, i can't say that standard volume proved any discernible advantage over moderate volume, was just more work and more time-consuming. Volume might help when refining for a contest.
