In researching agents, I found two categories: those who rep "one book at a time" and those who take on a writer for a contracted amount of time, or perhaps "career." What is the benefit of the former situation?
One book at a time means the author and agent contract with each other for the one book (and presumably for the option book if there is one.) The other option is the author and agent contract with each other to work for all the work a client will do.
The benefits of One and Done are:
1. If you decide the working relationship isn't to your liking, you're free to seek another agent at the end of the project. When querying for the next book, it's a whole lot easier to say "my previous agent
repped books one at a time" rather than "my previous agent and I didn't get along."
2. You're not committing blindly to a future you know nothing about. You're in for a year or two at most.
Both of these are true from the agent and the author point of view. If the client turns out to be a troublesome diva, well, the next book isn't automatically your problem.
I offer contracts for careers, not books. The reason is I've found over years of experience that first book may not be the first one I sell. I prefer to be in for the long haul at the start. I want my clients to know they can have confidence for the long term.
Of course, there's a 30-day termination clause so either of us can end the representation agreement without cause at any time.
There's a lot to be said for both types of agency agreement. When you're interviewing all the agents who offer on your book, ask them why they offer the type of contract they do. Make your decision based on that.