I always have recommended reading 5LL more than once.
The first time was right after the bomb (because I no idea that I needed to). And the first time ended up being a "How to fix this" guide in my mind. And a " boy, I really effed this up" guilt trip for myself.
I was trying to apply the concept, and trying to force what I felt was her LL to her. After a few weeks, I realized that it put way too much focus on her, and the dead Marriage. And it made me feel as though I was manipulating, or at least trying to manipulate her feelings, instead of validating them and working on my own junk...
The second time that I read it, was about a year into DBing, and THAT was when I really started to appreciate the content, and how it related to ME, instead of picking up the broken pieces for her...
It's a great read, just be honest with your motives....