Honestly, I think stuttering is a very personal thing. What works for someone to decrease it, might not work for someone else because they have other psychological issues. Example: If your teeth look very bad you might stutter because you feel uncomfortable opening your mouth to the full extent and show your teeth to the person you're talking to. This could be a psychological reason for why your brain fucks up your fluency (obviously in relation with genetics, because stuttering is in the genes).