The people he coaches yea they tend to forget to use a crutch because they haven’t practiced them well enough to use them in pressured situations. They use it only when they’re getting coached and don’t bother putting in the extra work that you need to do alone to master using them. I myself have used the crutches (now we have a speech plan) all day every day when I was doing the program and they helped me get out of difficult pressured situations because I was disciplined enough to do exactly what the book told me to do every day without excuses. Now I don’t even use the crutches cuz I can talk perfectly anywhere I want. Funny thing is that his website is full of people that have stopped stuttering (including myself) that have gave a speech and it’s all video recorded. Since you know it’s cause why haven’t you cured your stutter yet? I lift weights 4x a week and have heavy days where it’s really taxing on the CNS and to be honest I don’t see a difference after my intense workouts when I used to stutter. So I know know your theory is flawed