My current work is a mish-mash of detailed but informal planning, and my usual "Let's just see where this goes approach." The idea and world of the novel is one I've been carrying around for years, but I didn't want to write it until I felt I was better at the craft, so I just let it percolate, bringing up odd conversations and questions about its world with people in various discussions and then packing those answers away.

So when the time came to actually write it, I have over a decade of musings about the world itself to pick from. But actually writing it meant only having a clear image of the end, and a couple of events in the middle, with the rest of it being one big question mark, and starting the writing to answer those questions and find out how the hell things got to that ending event.