This is a topic which has been debated plenty over the years. If you go into a bodybuilding forum, you will read all sorts of numbers from 4-6 reps, all the way up to giant sets of 100 reps in one set. The truth is, there is no real right or wrong, only a basic guide.
We are all unique in our DNA, the way we eat and how we supplement. Some of us can handle a lot more intensity than others. While some people struggle to switch on to train above 10 reps per set mentally, others love the endless challenge of way more than that.
I have always found that a rep range of around 6-12, alongside forced reps and occasional drops sets, is ideal and works really well for packing on mass. As far as sets, I’m pretty set on 2 working sets and 1-2 warm-up sets as my ideal formula. I find if I have truly gone to complete failure twice, my 3rd rep set is very weak and almost de-motivating.
Remember, the key here is to get stronger over 8-10 reps, not be able to do that number for 5-6 sets. If you can max out on a rep range of 8-10 reps for more than 5 sets, you’re not really hitting failure in those first sets, or you’re resting way too long between sets.
Let’s get some facts out there. Feeling the burn over a long duration set, will not cause muscle growth. While lifting insane weight so heavy that your whole body is shaking and your eyes are bloodshot, will not help much either. Growth stimulus from resistance exercise is caused by a combination of mechanical tension and fatigue induced metabolic stress and to some degree, muscle damage.
In short, when you optimize mechanical tension and metabolic stress, you will maximize muscle hypertrophy (growth). The best way to do this is to pick a weight in which you can apply maximum load versus tension, to the working muscle. We have found that anywhere from 45-90 seconds of work is the perfect duration to hit this maximum stimulus. With a weight which you can control, using full ROM (range of motion), is key to really hit the muscles with maximum intensity.