I had "speech therapy" while going through school, mostly in elementary school in the early 90s. That did virtually nothing, though the teacher basically knew she was in over her head and told me/my parents that. She set up a thing for me to go see a proper speech therapist at Purdue. That one time thing helped more than anything she ever did, but it wasn't enough for a long time. In my mid 20s I went through Voc Rehab near me to go see a proper speech therapist again at Purdue(actually ended up being the same guy as before, though I mostly worked with his graduate level students). I went there for about a year and it was life changing, at least in terms of my speech. I still stutter, but it's way more under control and when it gets bad I can manage it much better. Mentally it's made it way easier to handle. I suppose that's relative, it's still a significant source of stress and depression, but not near as bad as before. But I went from someone terrified of ever even speaking online with people to raid leading in WoW, streaming on twitch, and even being close to outgoing when out and about in real life. I would highly recommend anyone give speech therapy a chance. Even multiple chances if the first one doesn't work.