Andrew, I've seen you do this with the ladies subconsciously, tailoring how you interact with each wife to best husband her as an individual. That, combined with the fact that your wives are awesome as individuals, is why I think your family is so successful where so many others fail.
I'm not going to argue with you about the book. My experience reveals a pattern. YMMV.
I do have to respond to the above, though. First, a story:
When Cheryl and I first agreed to lead a youth ministry, the outgoing leaders handed me a stack of 8-10 books on how to relate to youth, thinking they were doing me a favor. They were, but not in the way they intended.
I had already started to notice the difference between people ministering out of their head knowledge and people ministering from the Spirit. I heard the Lord telling me to pass on the books and trust Him. That approach has characterized everything I have done since then.
Don't get me wrong: I read more than most, and for those familiar with Gallup/Clifton Strengths Tests, "Learner" is my top strength. Loves me some reading. But in matters of relationship I have found prayer to be the way to go.
Another story: Many of us have had some experience discipling younger believers. How long did it take you to learn that your opinion of what the new believer needed to work on first was not always the same as God's opinion? To realize that we're more concerned with appearances, symptoms, and cultural 'propriety', while the Spirit of God goes straight to the root heart issues? That programs and curricula can be useful for learning facts, but they can also displace practical wisdom gleaned from being attentive to the Spirit? ("My sheep hear my voice, and follow Me.")
Okay, so having said all that, I have to correct your assessment of our family. First, there is nothing subconscious about it, and second, the ladies would shove each other out of the way to be first to testify that any awesomeness they're given credit for is a function of daily attentiveness to the voice of the Lord. That's all we've got, and it's all we need.
Footnote: I want to be clear about something. I have no ego invested in whether anyone reads the book or loves it or is offended by my opinion. If it's working for you and helping your marriage, good on ya, mate! But we get a lot of "how do you do it?" inquiries, and the answer is it's 100% the life of God in us. No books, no programs, no natural abilities (usually that's what we have to overcome), no degrees in psychology or family counseling. Just praying and listening and doing. That's our secret.