I uploaded, fixed, and re-uploaded the cover for Wild Nines probably at least a dozen times. I adjusted sizes, coloration, font styles, placement, and more. Amazon lets you see how your thumbnail appears online, lets you preview your ebook and your print book, and in that process see all the little things that you might have missed. It’s basically a way to get slapped in the face with your own inadequacies.
But, and this is key, the thing doing the slapping is a faceless machine. It will not buy your books, it does not care what is in them. Your tome describing the various methods of Platypus courtship techniques in haiku form means no more to it than Hamlet.
To your readers, though, those are the slaps that will count. Wild Nines, being just launched out into the wilderness, doesn’t have any reviews as I write this. I could very well find myself slandered for a giant plot hole I missed. Tarred and feathered for misplacing several commas. Eviscerated for ellipsis overuse. People with a hatred of orange colors might rant about the cover.
I think, though, that the book is ready. It’s been tweaked, read by others, edited, and read over my myself at least four times over. After a certain point, you have to let it sink or swim on its own merits.
Barring big name potential, authors these days need to depend on content, and a good volume of content, to make a living. For most people that means a compromise between absolute perfection and production speed. Is it better to write four books at 80-85% quality or one at 98%?
Only you can answer that question for yourself, but one of those has far greater odds of getting you a living income. Take a guess which one that is.