I have never done HCRI (knows someone who has), but I did a very similar program multiple times in the 90s. I think you get a lot of relapse because what they teach you is very hard to maintain in a lot of situations, especially in the manner they teach you. You will get a lot of fluency right after, but I think the majority of people downtrend a few months later, even if they are "practicing their skills" My personal experience... I was very severe (the director told my parents I was one of the worst they ever seen)... I think if you are severe and have zero control I think they can give you tools to get to.a point where you can communicate better, and you won't go back to the original state. I was still severe for a long time after, but never to the point where I initially started. I do not recommend a hard-core fluency shaping program, which I believe that's what HCRI is(or it was at the time, correct me if I am wrong).