I'm an extreme improvisor. I wake up slowly each day. Sometimes a person, place, or action comes swimming up from my under-mind. I must get out of bed to capture it and exorcise it. Almost always this will start a story.
Each day I discover the next step in the story. Each day is leaping off into the abyss. After two decades I've found that I always fly. When I reach a still point in the air I teleport to another story. Or to a day/week/month mini-vacation. Ten books published and still earning money I've found my process.
I always have more than one story to work on. Right now it's five books and three shorter stories. (Yes, I'm retired. I write whenever I want, no matter what time the day or night.)
Or I don't write at all. I know after two decades that inspiration will always come. There are too many books, TV shows, movies, daily or special events, or artwork and music, to spark off inspiration. I can't NOT have inspiration. My idle consumption of even the silliest or most trivial entertainment just stores up treasure to be mined for inspiration.
(Though MINING is a poor metaphor. For me NATURE is a better one, as inspiration grows without me seeking it, often surprising me when it arrives.)
That's me, my process, perhaps no one else's.