I'm a speech language therapist. I took a stuttering class in school (taught by a professor who stutters) and he said it's just the effect of having a novel circumstance and it goes away eventually. His clients all experienced this. What he means by a novel condition is if you talk differently than usual. Like if you sing, or act (a lot of actors have stutters), or try talking to a metronome. For whatever reason, novel conditions stop or decrease stuttering. Once they stop being novel, though, again for unknown reasons the brain starts stuttering again. Tldr: don't waste your money