i don't think there is a straightforward answer -- i am a 31 PWS, and i had speech therapy as a child. to be honest, it was traumatic for me, i'm still bitter about it. it sounds like you know what to look out for, but not all speech therapy is good therapy. i got put in speech therapy when i was in second grade. the office would call for me to go to the speech therapist's office and it was always embarrassing because the kids would laugh at me or ask why i was going when i felt super insecure about it. i often was grouped with kids with learning disability orders, so i think i had weird feelings about having an inferiority complex or not being smart or something. i told my parents about it recently, and they were horrified about it, they never knew. it's ironic because i ended up getting a phd at princeton and working at mit for a period of time, and i wonder if it's because of this feeling that i had to prove to people that i am intelligent! he told me at times that i had to work hard and not screw it up because otherwise i would continue to stutter for the rest of my life. he talked about a guy who would only order a ham sandwich in his adulthood because he wouldn't stutter on it. i had this "dread" from some of those admonishments that my stutter was my fault of not working hard enough, that there was this flaw or something that i couldn't shake. i "completed" the speech fluency course when i was wrapping up elementary school and i went into junior high. with the change of scene, puberty, new insecurities, my stutter got worse and the therapist "sneak attacked" me. i had to do a mock interview for my gifted class and i stuttered badly throughout. i was called to meet in a room and he was there (haven't seen him for a year or two by then) and he said in a stern voice that we need to go through the video of my mock interview. i was humiliated and i got so angry, i told him i would not be put through this and stormed out of the classroom. likewise, he asked all my teachers how my speech was and my mom read the responses to me and at least one was like "he has a severe stutter" and i felt like such a fucking loser afterward. so, be forewarned, not all therapy is good therapy. if your son truly does not care about it, who knows, maybe he will care about it afterwards. maybe he'll lose his inflection or a lovely characteristic way he has of speaking. i am getting angry just writing about these experiences, i sometimes feel like tracking the guy down and telling him how badly he did his job. it's funny how poorly trained most speech therapists are out there. maybe your son does care though and he's just too ashamed to talk about it openly with you and maybe he'll meet a great therapist that helps him out, you just never know!