Questions about Self-Therapy for the Stutterer by Malcolm Fraser

Questions about Self-Therapy for the Stutterer by Malcolm Fraser Hi. I know this book comes up on here from time to time and that it's listed somewhere here as a recommended book. I have a question that I don't see answered in my searches: It was first published in 1978 and from what I'm gathering has been little updated since then. For those of you who have used the book, do you find any of it outdated? For instance, in 1978, there may still have been more of a psychological explanation for the causes of stuttering rather than neurological. Or, if there are fluency shaping techniques, perhaps they are ones that have largely been replaced by better ones? I know that it's still in print and selling, so I imagine that it must have worth, but wanted to hear your opinions on this question. Plus, while you're at it, anything about whether the book was helpful for you, if the techniques are reasonable or take an amount of work that many people would find it difficult to be consistent with? Is it organized in a way that gives structure to someone using it on his own? Thanks. I do not stutter myself. I'm researching this for a friend.