Ah, perhaps the "goal-slipping" feeling is like the plateau. Your circuits are myelinating all the while, yet in your mind you might feel like you are not progressing at all. Then one day a magical leap happens.
I have to admit that I didn't listen to part 2 of the book closely at all. Part 3, about coaching, I did listen to intently. It explains what good coaching is and why it's needed.
I can tie together both thoughts above with an example of the kid I am trying to teach to swim. At first he started progressing with the help of floats and fins--not constantly though--and towing under my instruction. The purpose was to develop the feel for kicking and streamlining at least from the chest down. The progress ceased after I began teaching submersion of the face. He also went away for 10 days which didn't help. When he returned he just didn't come to the pool much and didn't work much at swimming. Though, all the while I noticed that he watched how people recover their arms.
A couple weeks later I placed the kid in YMCA group lessons. Since my objective was to make him a swimmer, I was willing to do whatever it took. Magically, within two days, he is now willing to submerge his face, he can float on his back well, and do a head-up freestyle across two lanes. Though I felt like a failed teacher at first, now I realise that what I taught was the foundation that allowed what seemed like immediate progress at the Y. While his level of motivation fluctuated, his body maintained the feel for the water and he could do more than he thought possible.
I saw the same thing with an adult that I coached only two times for pay and a little for free. I felt like a failed coach because no more lessons were requested and the student tended to sink by design. Well, the student persisted with what I had already taught and became more floaty. Later I saw him swimming head-up with a breaststroke-like arm stroke, which I had also taught him. (I gave him some advice on that.) In this case, the student was able to do what I started to doubt was possible! (I did try to video tape the sinking because it was so extraordinary. hehe Unfortunately the camera switched to still mode when I inserted it into the waterproof case.) I helped lay the foundation for learning. So with that I'm content.