I haven't published any novels for a while, and there's a reason for that: for the past three-and-a-half years, I've been working on a single book -- and, since it's the first of a trilogy, it's taken me much longer than my two-year average. (The plus side of this is that the second book will only take a year or so.)
I talked in a previous post about the necessity of other professionals to help with your novel, and so I'd like to demonstrate that I do this myself. Here, then, is a timeline of the last year:
February: finish rough draft, send to two critiquers. After receiving their critiques and considering for several weeks, I begin to rewrite the whole book, making massive changes.
September: finally finish the rewrite. Send back to my original two critiquers and to three new critiquers. (This was overkill; two would've been plenty.) A receiving their critiques and considering for several weeks, I begin to add interludes, to a total of about 11,000 words. I also do a complete copy-edit.
January: finish changes and send to first proofreader, whom I also ask for critique. After she's finished with it, I copy-edit the book again myself, including the most effective editing technique I've ever found -- reading it aloud. After that, I send it to my second proofreader. I also, during this time, send portions of the book to a gun expert to make sure my facts are straight.
February: send the book to my third and final proofreader. After I get it back, I again read aloud the beginning of the book to make sure I like how everything sounds. I will probably read the whole thing aloud again before the book is published.
So there you go -- eight other people who've read the complete manuscript. And the book is much better for it.