The answer is that I have no idea, but I had the chance this month to be a beta reader of someone else's manuscript. I'd never done this before, and it's kind of exciting. Hot off the press. Not even out yet. Being one of the first few pairs of eyes to ever read something. On the other hand, it's a little bit daunting, too. Because manuscripts (and this was a particularly long one) are like kids to their creators. So to end up with several pages of notes and suggestions for someone else's manuscript can make a beta reader feel like she's being kind of bitchy. Oh well. Feedback is a gift, right?
It's a wonder then that I don't ask for more of it with my own manuscripts. This author has a whole group of beta readers, whereas my books go to press with me and my editor as the only ones who have ever read them. For me it gets too complicated to get a bunch of hands in the pot, even if they are the hands of my most trusted friends and family members. I start feeling torn and indecisive if said friends and family members disagree on certain elements, so the best I can do to stay sane is to just move forward with the book the way I like it best. Of couse, when you write non-fiction, it's probably easier to get away with this. I don't have complicated plot twists and character development to worry about, as did the author of the manuscript I just beta-read.
At any rate, I was flattered to have been asked, and am always impressed by people with the discipline and talent to create entire books. They make the world--and my life--much more entertaining.