A similar thing happens fairly commonly on college campuses. A professor will use their unpublished book as a textbook for the class. Whenever students ask questions about the content of the book (which they no doubt will, eventually), the professor will then update the book and use it in another class until they receive little to no questions about the topics and it appears to provide a functional understanding of the topic. I know quite a few who will ask that their spouses or close friends work through the book, then will talk with them about the content and their understanding when they've completed it.
When writing Storm Applied, did you test it out on any of your new developers during the onboarding process? It sound like training your new employees influenced Storm Applied.