I Have This Problem
I start, and before I am done, I keep on working on the parts that I have already written.
It’s a bit of a hyperbole, but a lot of people do get stuck in an endless cycle of editing and never make it to, “The End.”
Editing as you go has two fundamental problems:
1) It will slow you down. If motivation to write is a problem for you, this is the kiss of death. A consistent stream of progress will keep you motivated long enough to finish the book, which needs to be your #1 priority when writing. A completed novel that needs a lot of additional work is infinitely better than a half-finished novel of perfect prose. It’s better to have three new sentences than to obsess over whether this one old word is the best possible choice.
2) It’s futile. It’s impossible to tell exactly what your novel needs until it’s done. Do you think all that foreshadowing, characterization, and repeating metaphor in famous classics were in the first draft? Of course not, at least not to the same degree. That’s not how writing works. Once you get to the end and go back to the beginning, you’ll notice flaws that you never would’ve been able to see while writing. Your protagonist will do something in chapter 1 that you won’t realize is out of character until you’ve written chapter 30. You’ll notice that snakes showed up once in chapter 7 and again in chapter 12, and you realize that this would make for a neat motif so you insert them somehow into chapters 1, 4, 18, 19, 24, and 33 to underline moments when the villain is secretly acting to undermine the hero. You’ll realize that the wizard from chapter 5 is doing things that directly contradict the Rules Of Magic you explain later in chapter 26 and tweak things so that he’s more consistent. None of that would be possible without having the completed book in front of you.
Now, I’m not going to say you should never ever do any editing while you go (my guilty pleasure is editing what I wrote the previous day) but it is imperative that you limit yourself to the bare minimum of editing until the book is completed. If the book isn’t completed, you should never, ever go more than a day of writing without writing something new. Staggering editing days with writing days is far from ideal, but at least it will force you to keep writing new material consistently.