Think of what you skip reading a novel: thick paragraphs of prose you can see have too many words in them. People don’t skip dialogue.
This may seem to be self evident, but to the writer, and particularly the new writer, it’s not. We often think that what we have to say is so important, and that our writing is so brilliant, that we can go on for pages, and readers will be so enthralled that they will plow through it, absorbing every word.
But think about what you might skip or skim. I bet it’s a big fat paragraph, or page, or pages, of dense prose. But I bet you don’t skip dialogue. Why not?
Because that’s where the story happens. We want to see people interact with people. We gain insights into the character by what he says and how he says it. This is all particularly true with commercial fiction, as opposed to literary fiction, which probably explains why it’s so hard to sell literary fiction.
Obviously, a novel can’t be all dialogue. That’s called a play. You need prose. But there has to be a balance. A rhythm. And if your prose goes on for more than a few paragraphs, it had better be pretty darn good, and contribute materially to the story.