I used to be a project manager. I know how planning works.
When I write for work we have a very structured process. We use a “pyramid structure” where everything has a main heading, then subheadings and bullet points in increasing detail. So every sub-point beneath a main heading always supports the overall argument of that section, meaning each section is self-contained and complete. One of our ex-editors Josh Bernhoff explains it here.
It works. For business reports.
I didn’t apply this approach when I started on a novel. I had a rough idea of my story. I knew the end. I spent time working out the characters (backgrounds, motives etc – much of which changed as I wrote) then I sat down and started typing. I had a blind faith that everything would fall into place. It didn’t. I stalled 3 times.
Having rewritten my first 5 chapters 3 times before I got beyond that, I realised I needed a new approach.
I built a plan.
A chapter by chapter plan which gave a single paragraph synopsis of each chapter. I then worked backwards form the chapter count and created a quick spreadsheet to estimate how long each chapter had to be to hit somewhere between 80 and 100k words. When I then sat back down to write, it happened very quickly. It took roughly 4 months to write 20k words 3 times. Then about a month of planning. Then about 3 months to write the remaining 75k words.