Like many specialisations, authors can become pigeon-holed and that’s what my agent wanted to do to me. I don’t think they did this to be mean or even close-minded; this must have been a strategy that worked for them in the past with their other clients. But being restricted to one type of writing or one bookshelf didn’t work for me. I had lots of ideas, and lots of stories to tell (still do).
As it was explained to me by this agent, publishers wanted to see that you were “serious” about the genre - in my case, mystery/thrillers. If you diversified your offerings (this week I’m selling a YA from Angela, next week, I might be selling a picture book from Angela) it seemed to indicate that you weren’t sure what you wanted to write.
This is an approach that is publisher-focused as opposed to audience-focused. The agent was entirely concerned with selling this idea/book to a publisher (which makes sense since their biggest earnings come from the percentage of the advance you get from said publisher).
As a reader, when I’m hooked on an author, I read as much as I can that they have written, I am not bound by bookshelf and I don’t know anyone that is. In fact, when it comes to discovery, I’m not even bound by author. I often find new books to read based on recommendations from friends, or awesome Indie bookstore staff.
For my own journey as a writer, I’m much more focused on my readers than the publishers or the agents. My readers are in it with me for the long-term (and I’m in it with them).