I thought that it was stupid that Brandon Sanderson had the narrator of Tress of the Emerald Sea call all the unnamed sailors "Dougs" when he could have just called them, you know, sailors. But then I started using the term. Turns out having a word for "yes, we know that realistically all these individuals have unique identities and personalities, but they're not the focus of this story so we're going to treat them as faceless background characters" is surprisingly useful.