Different training systems suggest an endless array of often conflicting recommendations regarding exercise selection, number of sets and reps, length of rest periods. One system says 3 sets of 10 reps; another says one set to failure. One system recommends resting 1 minute between sets another says 3 minutes. One system employs a partial range of motion, another a full range of motion. And on and on…
Here's all you really need to know;
"When a biological system experiences a challenge, it modifies itself in order to be able to more easily meet similar challenges in the future." Charles Staley
That's it. That's the whole story. No matter which training protocol you choose, out of the thousands available, if it will accomplish the above requirements it will work.
Now, some protocols are more efficient than others. Some are more complicated than others. Some may fit your genetic makeup or your physical circumstances better than others. But if they meet the above requirement they will work. If they don’t meet those requirements, scrap them.
But for any protocol to work, it’s up to you to make sure the biological system is challenged - forced to do something it hasn’t had to do before.
Every day, every workout, every set has to be a challenge. One more rep, one more set, one more plate on the bar, one more 40 yard sprint.