I really hate when I suddenly have a new idea while working on my book. At least when it requires going back three chapters to remove an entire section or add in a new character or something like that.
I like organization and when I have to rework entire sections it gets me all flustered.
Recently I started using note cards to organize my book. One note card per chapter. Each card has bulletins noting the main events of each chapter, as well as what month the chapter is happening in.
So far this has really helped me out. Now when a new idea pops up I can just savor it and happily work it into the story.
Yay note cards!