Wow. Check out this article: NY Times--'Writer’s Cramp: In the E-Reader Era, a Book a Year Is Slacking'.
Big authors are being told to write more, so they're not forgotten. Right before a big release, the big publishers also want the authors to put out a novella, so their name's out there for everyone to see.
So is more better? I'm not so sure, but it does help with marketing. However, most people have 'day jobs' and can't write as much as someone who's home all the time (and refuses to clean because of her 'writing job'--um...that's me). Is it possible to write a book a month, from scratch? I release around a book or so a month, but mine are already written and on my computer, so that doesn't count.
The market is evolving, for sure. This is a 'I want it now' society, however, if I wait for something, it seems so much sweeter than having it instantly.
What do you think?