There is a derogatory term out there for agents known as being a, “spaghetti agent,” which isn’t the type of agent anyone wants. Nathan Bransford probably explains it best here, on his blog:
But, did you know you can also write too fast? Or, maybe too much? I didn’t either, so, let me explain. When the first book is on submission, but you’ve yet to acquire a book contract, it certainly doesn’t hurt to write book number two. Matter of fact, most of the time you’ll be praised for doing so. It shows professionalism, and dedication to your craft.
However, know that it may only serve it’s purpose if your first book doesn’t sell, and it doesn’t need to come along too fast.
Because editors have steel traps for brains, for one. Despite all that reading they do, they will remember your name if it comes rolling across their desk again too soon. What I mean is, if they rejected your first story, they won’t forget that as quickly as you think. (yes, potentially even a year later.) So what’s supposed to happen if 1) your first book hasn’t sold six to nine months later, 2) you already have book number two just waiting in the wings? Consider these two scenarios:
First, there’s a story about an author and her agent, who couldn’t seem to get a publisher interested in her books – not any of the four her client had written. The reaction to her client’s name after the second rejection, was “oh geez, not another book by so and so!” amongst editors at the publishing houses. The thing was, her fifth book, according to her agent, was probably her best work yet, a brilliant story as a matter of fact. They decided a pen name was in order and the book was submitted under that. The good news is, it sold. But imagine how that author felt when her previous work, associated only by her name, was rejected simply because of that. Editors didn’t care to read any more of her work, as I recall.
Second, if your first book does sell, and you end up with a two book contract, you only have that because 1) your publisher liked your first novel, and 2) they will have a say in what gets published next since they are going to be the one to pay the advance, and 3) they might not give a damn about that great story you already wrote about “The Werewolves of Hipperdoodleville.” You would have wasted a lot of effort for nothing.
I’ve only learned about this, as I was happily getting ready to churn out book number THREE. There is a finite time between submissions before expecting your agent to stick another story into a new line up. And, consider that it’s possible your effort may only come into play if your first book doesn’t sell. This is a hard thing for writers, like me, in that I’m addicted to the process of writing. I have to have something current to work on, or I feel at loose ends. I plan to still keep writing book three, just at a much slower pace. I don’t want any editor to think I’m just throwing something at their wall to see what sticks, like spaghetti.