For me - showing a half-finished manuscript is tricky. Just as a bird will get spooked and abandon her eggs if some outside party comes around and makes too much noise or pokes around the nest too intrusively - well, that's what it's like for me if I show work too early and I get a lot of editorial suggestions at the wrong time.
Donna TarttTaking on challenging projects is the way that one grows and extends one's range as a writer, one's technical command, so I consider the time well-spent
Donna Tartt