It is true that when Mister gasped at my threat, he didn’t know that it was right on cue. But when I cue my characters, the readers have to know who is speaking. There are more ways to do that than just “[character’s name] said.”
In one of my WsIP, the antagonist chews her hair. She often has to slurp her spit back in to her mouth before she can speak. Gross, I know, but I always know its her and I think the reader will too.
Many published works use cues like this to let the reader know who is speaking. It has made things like popping gum and twirling hair a little cliché. So, as a writer, I have to be even more creative in deciding my cues.
Here is a link to a great study that can help: http://users.soe.ucsc.edu/~maw/papers/personality_jair07.pdf. I like page 5 in particular. It lists common linguistic habits of people with certain personalities.
Especially in children’s writing where the word count is low, every word has to work for me. If I can use a matter of speaking as a way of showing characterization, my words are working double. And it can help me spread character traits through the story rather than having one front-loaded description. Works for me!