Depends... the first actual "whole" novel I wrote was based on an RPG campaign. It was a lot of adapting, a lot of combining scenes and short stories and finally one summer I took 9 days off of work and sat down, eight hours a day, and wrote to fill the whole thing in.
Novel #2 was a NaNoWriMo novel. Started on Nov 1 with an idea for an opening scene, wrote that up in a couple pages, stopped when I got out what was in my head, and each day I could see/wrote down "a little more" Was able to finish it in the month. Not great art, but it has a plot and a reasonable amount of coherency.
Novel #3 was a 3-day novel (gonna do that again this year), I knew I only had so many hours, so I took time off work, and wrote out an outline beforehand. Made sure I got enough sleep, and wrote ... maybe 10-12 hours (in chunks) each day and did get it done.
So I guess it depends. Whatever way or ways work - go for it. Maybe a few will.