When I was writing my first novel, I was so excited to see my own words on the page that I ended up with several scenes that didn’t have much at all to do with the main plot. After I signed with an agent she pointed out this tendency to wander and had me cut a lot out. I mean a LOT. It was painful to hit the delete key, but I realized that she was right.
When you’re writing a novel, make sure each scene has a purpose. If you go off on tangents that have nothing to do with the plot or aren’t going to somehow tie back into it later, your readers are going to get confused, or bored, and they may stop reading entirely.
I recently finished reading a murder mystery that veered off in several directions with new characters who seemed interesting enough, but then they all disappeared and never wound their way back into the story. When the killer was revealed and the book was over, instead of feeling satisfied I found myself scratching my head and thinking But what happened to that little blonde girl on the side of the road? And why didn’t I find out what the deal was with that creepy truck driver guy? And where did that wise old lady from the restaurant go?
It was as if the author couldn’t be bothered to finish writing his own book.
Having subplots can keep a novel interesting, but they need to keep the overall story moving forward. If they go nowhere, your story goes nowhere, and your readers might end up going somewhere else for their next book.