I read it maybe 6-7 years ago, and no, it hasn't had much if any effect on my speech (which is mostly passable these days). What it did for you is basically what it did for me: validated the suspicions I had about the origins of my blocking. I had a relatively traumatic childhood and have anxiety and a bunch of other problems stemming from that, and blocking and anxiety have always been highly intertwined for me, so… Yeah "speech therapy" doesn't seem to care much about the why. I've never found it of much use because it was always about coping mechanisms (which are useful, don't get me wrong) and not working on the root problem, which frustrated me.