I'm an old guy. I finally found after trying a lot of different kinds of therapy. What finally worked for me took 3 things. 1) Techniques to deal with my type of stuttering. Diffferent types of stuttering require different techniques. 2. Mind training. What I mean by that is that most of us have been stuttering so long that our brains get "wired" for it so it becomes a habit just like anything else you have done a long time. So mind training helps to break the bad speech habits. 3. A very strong support system. I practiced the techniques with other people who were on the same plan several times a week on zoom calls. This is what finally worked for me. It took a lot of work but it was worth it.