Even if you're improvising, the fact that beforehand you know certain things will work helps you make those improvisations successful. It really helps to have a certain amount of knowledge about musical structure.
“A very wise author once said that a writer writes for himself, and then publishes for money. I write for myself and publish just for the reader.”
“So I turned these sort of deficiencies into a, a workable thing if you understand what I mean.”