Okay, I had an epiphany today--I discovered a "flaw" in my w.i.p. I put flaw in quotation marks because this one is big enough to drive all the semis delivering the last Harry Potter through, side by side. The problem is I developed, added to and changed the characters, after taking Donald Maass' Write the Breakout Novel Intensive workshop (excellent), which transformed relationships which meant that a plot point disappeared. Vanished. Gone and left behind a black hole.
I'm fortunate to have an excellent writers' group that I credit for much assistance and for most of my improvement of my writing. They didn't catch the plot hole. Why? Because they had read the earlier drafts, of course!
Hence the value of "blind readers." A term which always puzzles non-writers--do you have to translate into braille? Not unless the reader is literally (sorry, bad pun) blind. A blind reader is someone who has never read any draft or section of your w.i.p. When the draft is very, very close to final is when you have as many blind readers read it as possible.
The blind reader is a great resource. They catch all the things that a writer doesn't: plot failures big and small, character problems, where the novel works and where it doesn't (especially important). Blind readers are not your family, your close friends or a possible agent. Blind readers are best if they enjoy reading and read widely in your genre or lack of genre, but are fine just as long as they love to read. Writers are nice as well as blind readers, but sometimes writers are too much editors. Blind readers are the closest thing to objective that a writer can hope to find.
How to find a blind reader? I have a librarian friend who has a couple of friends. I have a writer friend who belongs to a book club and knows a couple of avid readers. Book clubs, librarians, writers that have friends--are you friendly with the clerks at a bookstore? When you find a blind reader, resist the urge to make a new friend. Explain how you truly are thick-skinned (a little white lie) and would love to hear their honest opinion. If it's not too long and involved, a short quick list of questions at the end of your w.i.p. is also useful: "Were you ever confused or lost or did you lose interest in any of title of book?" Keep your interaction brief with a blind reader so they don't become exhausted and use each only a few times.
HINT: Blind readers are gold and well worth searching for and finding.