It doesn't matter how effective your training routine is, your body learns quickly and stops the muscle growth after a certain level. Even if you do negative reps which cause damage to the muscle fibers and enhance growth, they can become inefficient after a while.
Muscle mass can adapt to you routine if you keep on doing the same workout, and it can eventually stop with its growth. It is a common misconception to think that if you do one more rep, or add more weight your lift, it will give you better results. If this is your approach, know that it isn't efficient.