Books are Built with Nails
Nails are the tiny objects that hold a structure together. They are pretty extraordinary if you look at the size of a building and think it's a bunch of relatively small metal spikes that give it form.
It's said that the 5 elements of a story are; plot, setting, characters, conflict and action. But something that holds all of these great elements together are the details. The relatively small points that make the novel feel cohesive.
If the story takes place over a long period of time are the dates accurate, are the characters aging accordingly, do the seasons change? Throughout the novel, do the actors have a distinct voice? Do locations have the same physical properties from one scene to the next?
The details must be consistent.
There's an expression--it's the little things. When writing a book, it's the tiny details (like nails to planks of wood) that hold the creation together.