I use mind mapping only when super reading and dipping does not bring the entire book together.
I also use it when the material is something I absolutely have to remember.
I find it especially useful when someone gives me a book and will want to talk with me about the book when I'm finished.
Usually I am content with doing a mental mind map over the few days after finishing the book. It helps me put the whole book in perspective and I tend to find connections to other material or things in my life.
What serves as the basis? Depends on my purpose. I will generally take the main point relating to my purpose. Sometimes I simply take the Table of Contents and map away!