In commercial fiction especially, everything in the story usually contributes directly to the plot The shorter the story, the truer this is

Fiction is about stuff that's screwed up.

Anything said in upper-crust British automatically sounded intelligent.

Conflict is the place where character and plot intersect.

What characters do must grow out of who they are, and who they are is, in turn, influenced by what you make happen to them.

Religious reverence for one's own job, even if the job is worth doing, is a sexual turnoff.

Every paragraph should accomplish two goals: advance the story, and develop your characters as complex human beings.