And in that time, the writer changes, is no longer the same person she was when the idea was first born, when the first words were written. Life happens; the world happens. In the last six months, I graduated from culinary school and settled into a new routine with my job. And we've certainly all had more eventful periods of time.
We change; we edit. We change again; we edit more. But our previous outlooks, perspectives, and personas aren't completely erased with revisions, which makes a novel a garment of human layers, an unconscious history of the writer. Maybe that's part of what makes them so compelling ... and part of why we react so violently when favorite writers turn out to be bigoted, racist or abusive. We've had intimate contact with the development of their lives.
Unnatural Causes deals in part with truth and deception, with the right to privacy versus dangerous secrets. A (short) story I've been finishing lately, Based On A True Story, touches upon similar themes ... and the eyes that will go back to edit both have been forever changed by recent global events.
Of course, short stories often have similar, even longer, time lapses between original write and editing - and sometimes even beginning to finish. It's a matter of degree - just like length and complexity, really. A short story is a photograph; a novel is a video.