I tried it once and had a very bad experience, my speech therapist was a stutterer themselves but had it far worse than I do and they basically yelled at me the whole time to just deal with it and suck it up. Not only that, I was the only adult who would go there as normally parents have their kids going to these kind of things…bunch of kid toys and books in the office, etc..what did help me thought was not a speech therapist, but an actual normal therapist. To just have conversation about it normally helped a lot, and in fact..improved my speech a little too.