I’ve worked with a few manuscripts recently where the writers established and then promptly forgot about important threads. In my book, I talk about shining a spotlight. If something is important, it’s your job as a writer to shine the spotlight on it. You pick where to aim that light, and how bright it is.
What do I mean about dropping threads? Well, let’s say that your character is a musician. They speak in musical metaphors and seem to see the world through a Beautiful Mind-esque musical lens. Until this fades from the manuscript about a third of the way through. And music doesn’t really factor into the plot itself.
I often see this in manuscripts. Just like voice sometimes fades in and out (the writer is focusing on voice when they’re writing certain passages, then they shift focus to something else and the narrative tone changes), so do various other elements of novel craft.
Character attributes (musicality), secondary characters (a supposed best friend disappears for 50 pages and nobody thinks anything of it), world-building elements (the world is on the brink of war and yet there’s no danger or news of danger in the middle of a story), and plot points (the character says their objective is to seek something, then they get wrapped up in a romance and the desired object seems to fade into the background) can all be lost in the shuffle.
Your job as a writer is to analyze your story and see if you’re dropping any threads. Are you swearing up and down that something is important, then abandoning it? Does everything that’s vital to the story and introduced at the beginning wrap up by the end? Do all of the important elements get some kind of closure?
This is a common note that I give. “Whatever happened to XYZ?” Make sure your story feels cohesive from beginning to end, leaving nothing/nobody of note behind.