nonbreaking space said:
when people do it one way, they have no proof that they could have done it the other and still been successful. publish in a way that makes you comfortable/happy regardless of how anyone else has done it. you'll find people that have found success in every way possible: releasing n books at once, n per month, or one at a time whenever. i've released one book at a time as it was finished since day one (i've been doing this for over 2 years), and i've done well that way.
If somebody takes a look at the thread mentioned above
http://www.kboards.com/index.php/topic,198283.0.html
I explained my reasoning more fully in response to people's questions--why I think releasing several at once can lead to more success. But here, quoted again, was my first response:
But this isn't your favorite author releasing books. This is a brand-new author trying to get visibility. If somebody reads a book by an author and enjoys it, they think, "What else has she written?" Nothing? Umm...yeah. A month down the road when she releases Book 2? Mmmm....MAYBE that person is still looking for her book. (Or has pre-ordered it.) And more likely not.
That was what influenced my own decision--that customer behavior. And interestingly, I had a discussion with my agent along similar lines recently. She said, "a couple months is a long time in the book-buying world. You've moved on to another author and another book."
"But wait!" I hear you say. "What if I have a mailing list that they can sign up for after they read Book 1?" I finally got a mailing list a few months ago. It's got about 800 people on it. It's a good thing, I'm sure. But that's 800 people. And that's me, and I sell really well. So I'm just saying, YMMV on that mailing list. And when you're just starting out, with one book? That mailing list isn't going to be nearly as effective as having another book for them to read right away. It's all about traction.
The real x factor, of course, is how much they want to read your other books after reading that first one. That's the one that's really hard to predict. But if they DO--if they think it's awesome and they're excited to read another one--it's way easier if there that other one is, right there for them to pick up. So I'd release at least two at once, if I were starting out now. Then do your novellas once a month or something thereafter.
But, of course, everyone gets to do what they want, and I'm also sure that any strategy CAN work. My 2 cents, that's all.
*****
Of course, it would only be possible to test it with, well, a great big test, where a whoooooole bunch of authors in the same genre did it each way and somebody tabulated the results. But I think you just read the reasoning either way, and see what resonates with you--see what seems to make the most sense to you personally.