Writing can be fun and spontaneous. But when I want to produce something worthwhile, fiction or otherwise, I tend to start with a significant outline. Without a plan, I could always luck out with a good story, but even if I do, the mountain of editing work isn’t worth it.
I know other writers who don’t outline their work at all. Instead they just pick it up and go. (How fun!) That’s great for them but it doesn’t work for me. By the time I sit down to “write,” I’m already weeks, months, or even years into the project.