Hmm -- If I understand the logic behind the workouts right (and I'm really just learning this stuff) I'd guess that you could go on repeating some of the stages. The first one is really about learning the exercises and how to work out, and stage 6 is an oddball, but the rest of them could probably keep cycling through. But it's important to keep changing things around -- a lot of people seem to go from this to some of the workouts in the original NROL, or into a period of kettlebell work, or some other branch of strength training before cycling back around.