From what I hear it works for a lot of people. For me however, I cant seem to bring myself to do it in a high stakes situation because I can be reasonable fluent. I think it desensitizes you from the trauma of stuttering involuntarily, and also - theoretically, prevents you from getting those horrible surprise stutters that come out of no where and jerk your head. Sometimes in very low stakes situations I like to try it out. Like when I have to ask for a book at the library and I know I may stutter and get stuck so I do it to avoid that. But one time I was at Barnes and Noble and I went in to get a book and they asked me my name, and I said voluntarily H-H-Howtobe and the dude said, "ok Ms. H-H-Howtobe..." I have an African names so double syllables aren't uncommon. I keeled over in laughter, poor guy didn't get it. I couldn't be bothered to explain so I took my book and laughed all the way out of the store. He must've been so perplexed haha.