I'm a seat-of-the-pants writer. I may jot down the main story lines but other than that, my characters pretty much write the story, as is the case in Never Surrender. That novel happened when I visited my brother and his family in Dubois Wyoming. I can't actually explain what happened or how, but the characters popped into my head and created a movie-like image and I just wrote what I saw in my mind. Their dialogue, their feelings, their actions....it just happened and I wrote. I wish each book was that easy to write. With what I learned writing Fire On The Water, Never Surrender turned out much better and was an easier read.
Other story lines and character profiles are always coming to mind and I have a card file that I keep these ideas in so I can use them as I choose. I also have files of reference materials and that alone can get one carried away. I do remember while researching my first novel, my girls refused to go to the library with me after a while because I would never want to leave.