Man I don't know. If youre going to the gym for example, trying to gain or lose some pounds, you are not going to study human body, you will only do exercises. I am saying this because, I do one exercise myself daily and it helps me more than anything. And with stuttering is, like the gym, muscles. You need muscles in your jaw to speak, and with this exercise you do just that. Maybe there is something wrong in the brain as well, that's why you'll always have to do some exercises. But it works and life is easier if you can communicate normally. Say what you want but I am speaking from personal experience and I stand by that. I wrote an ebook about it, if anyone wants, i'll send them a free copy.