[jakejake]

I think the person with 30 unfinished books and the person spending 30 years on their novel are really just flavors of the same thing - inability to finish a job. They're both re-starting and revising over and over again. I would guess that if the 30-year novel ever gets completed, it probably bears little resemblance to the original draft. There's probably various reasons that could apply to either case - perfectionism, lack of attention span, unable to commit on decisions, self doubt, etc.