The scene-by-scene storyline has another very important function. Every new idea seems wonderful the first day, two days later it’s already less plausible and after a week it may seem very average. This is why I spend at least three months thinking about the scene-by-scene storyline because I want the story to seem as realistic as possible. Nothing must be left to coincidence.
I once talked to a writer who said that she sits down every day and begins to write. She never knows what will come out. Her system also works, but I think it allows for a lot of unplanned writing that can be superfluous. And some people find it very difficult to delete what they’ve written, which is a big mistake.