An exerpt from the Max OT website
What is "Positive-Failure"?
Positive failure is when a set is performed to the positive limit of muscle exhaustion. In other words, you are done with a set when you are no longer able to complete a rep on your own. This positive-failure should occur between the fourth and sixth rep. Max-OT does not employ forced reps beyond maybe partial help on the last rep of a set.
Contrary to what most have been led to believe, forced reps are counter productive to building muscle. They artificially fatigue the muscle, deplete muscle energy stores, and produce non-progressive overload just to name a few.
How many times have you seen people in the gym training and one guy's spotting another and yelling in his face to do two more reps when he really should have stopped two reps ago. Do not do forced reps.
4 to 6 Reps
This is the heart of Max-OT. You will do 4 to 6 reps on virtually all lifts. There will be some lifts that you will do a little more reps on, but only a few. The 4 to 6 rep range is important and critical to success of Max-OT. We will go deeper into the understanding of this further in the course, but for right now you need to ingrain this "4 to 6 reps" into your mind.
What is meant by 4 to 6?
When I say to do between 4 and 6 reps, this means that you will use a weight that is light enough to allow you to get at least 4 reps, but is also heavy enough to where you cannot do any more than 6 reps. If you can't do 4 reps, then the weight is too heavy. If you can do more than 6 reps, then the weight is too light.
This is important and is critical component of Max-OT. 4 to 6 reps is the "ideal" rep scheme for building muscle. It allows maximum muscle fiber overload and maximum muscle fiber recruitment.
Intensity
A big advantage (aside from the physiological benefits) is that it's much easier to mentally focus your energy on a set of 4 to 6 reps than it is on a set of 10 to 12 reps. Knowing that your set will be short and intense will allow you to generate maximum mental intensity, maximum muscle contraction, and maximum muscular force. Max-OT, in itself, is a more productive muscle building approach that literally acts synergistically with each technique, component, and principle to exponentially accelerate your results.
Once you understand that heavy weight is the most influential stimulus for muscle growth, you will continue to strive for greater overload. You will continue to get bigger and stronger in less time.