Comedy has some of the same. Some comedians look like they're just rambling through random ideas that have popped into their heads, when in fact it's a patter they've been practicing for months and months. I have a lot of respect for the ones who can hide the seams between their various jokes and make them look like the funny uncle at family gatherings just riffing off of people or themselves for an hour.
It's funny you say that because whenever I see a standup special and the comedian seems to randomly be prompted by something they see in the audience/off camera that leads them down a bespoke, yet perfect response/thread I have to think they are just making the prompt up.
I'd estimate about 20 years ago I saw a British comedian called Ross Noble who did this. He almost acts like he's got some form of ADHD where he is permanently distractible, will switch topics mid-sentence because something else gets his attention. Someone came in late, so he asked them what took them so long. Someone wearing a hat catches his eye and he makes a comment and goes off on some tangent. Those tangents can be minutes long. Eventually he always goes "right, now where was I?" and resumes the scripted/rehearsed part of his show.
And then... in the final minute or so of the show all of those seemingly random distractions and tangents come together to tie up the various stories and jokes he'd been telling! Decades later when I think about it it still blows my mind. They can't have been random at all. I've no idea if the various distractions were plants, or maybe they never existed at all and everyone in the audience just thought we were all too far away to hear whoever he was talking to? It was such a flawless execution though, only heightened by the fact he'd convinced you he was a rambling unfocussed mess for most of the night.
At UT Austin, there was a Physics class called "Pseudoscience" taught by Rory Coker(?). The class was on precisely the topic mentioned; it was a graded attendance-based class. (You lost a grade letter for every 1–2 classes you skipped.)
Rory was a master class mentalist — literally world famous. When other world class magicians were on the continent or passing through they'd come visit him. Invariably, he'd make them do a 10m opener for the class (usually mentalist, illusion, and close up). Did I mention the class average was a C?
Anyways, for the final, Rory did his trick: he chatted to us for a few minutes, drawing a picture; then we all had ~30s to draw a picture. Then, he chatted with some people — kinda at random — then picked one person to seal their picture in an envelope. At the end of the class was the reveal: he'd drawn this picture the girl drew. More importantly, just about everyone drew the same picture.
Then he made his point: depending on how he was feeling, there were about a half dozen pictures he could get an audience to draw.
Penn referenced it in an interview somewhere, with the impression he was citing a well-known stage magic quip.
Essentially: there are two ways to make something appear magical.
- One is a gimmick (physical or otherwise), which is performed so well as to be invisible to the audience.
- The other is simply doing something effortlessly that seems impossible without spending years of practice... but having actually spent years of practice on it.
He cited some Teller trick that Teller brute forced by just practicing the movements for an entire year until he could do them reliably and flawlessly.
This is as good a definition of stage magic as anything, I suspect.