For some reason, it seems like all people outline think that everyone else has to outline. Misery loves company perhaps?
I have not outlined for any book, any genre, fiction, nonfiction, etc. It does not work for me. Period. Not loose, not mind maping, no version there of. When doing formal engagements that require it, I build the outline after work is complete. I am not alone in this as many have pointed out. Successful authors like Steven King are doing fine without ever planing anything.
So if outlining is how you work, great! Do it. If not, great! Do not do it. Something else in the middle? Great! Do that!
Its really that easy