A gardener or an architect?
G.R.R. Martin has this famous quote about different types of writers:
I think there are two types of writers, the architects and the gardeners. The architects plan everything ahead of time, like an architect building a house. They know how many rooms are going to be in the house, what kind of roof they're going to have, where the wires are going to run, what kind of plumbing there's going to be. They have the whole thing designed and blueprinted out before they even nail the first board up. The gardeners dig a hole, drop in a seed and water it. They kind of know what seed it is, they know if planted a fantasy seed or mystery seed or whatever. But as the plant comes up and they water it, they don't know how many branches it's going to have, they find out as it grows. And I'm much more a gardener than an architect.
Brandon Sanderson uses the "Discovery writer" and "Outline writer" for the same concept. He's famous for being an "Outline writer" but admits that most writers, including himself, fall somewhere between these two extremes depending on the project.
The concept is not limited to fantasy writers. Often, authors mention how they approach the process in their interviews. Recently, I read this interview with Debra Spark, author of Discipline, and this part helped me to appreciate the futile "gardening":
Big chunks of this book got tossed out. Just not necessary or too wordy. But I have to write the pages to realize the pages don’t belong.
She then quoted E. L. Doctorow:
Writing is like driving at night: You never see further than your headlights, but you can make the whole trip that way.
So far, I haven't found the magical doors of writing fiction without a plot. Maybe it's because I've never driven at night, and I don't know the feeling. The idea is fascinating anyway—the writing without a plan, not the driving.