What you think about stuttering makes a lot of sense bro. Maybe the "level of difficulty" of a real-life situation is much higher than the therapy practice, and that makes it harder to use the techniques. Concentration, focus, and practice, I agree 100% with you. I think we tend to enter automatic mode when a real social situation begins and we forget to use the techniques and do the bad habits we learned to do by all those years of stuttering. Maybe we need to break that unconscious state for us to be capable to use the technique. It's going to be a hard road bro, but we have no choice but to be stronger than that.