I’m a proponent of planning novels… up to a point. Compared to some, they’d classify me as a pants’er.
I write three different sets of numbered lists where I place between a 5-9 word summary of what the scene is.
Once that’s done, I usually (!) can write an entire novel very quickly.
However, every now and then I’ll realize mid-stream that there needs to be an additional scene I hadn’t planned on.
Say somebody buys bad food in scene 12.
Scene 13 has to be them getting sick from the food.
It usually stops me cold mid sentence in scene 12.
No worries. I’ll find a way to compact the story elsewhere.
Be prepared for this, working on your own novels.
