The “3 reps” thing is from my training as a hypnotist. Once the brain is exposed so some stimulus 3 times, the pattern-making/pattern-seeking mechanism kicks in.
Anything last 3x locks the pattern in more.
Look at most jokes you’re told. “A priest, a rabbi and a rabbit walk into a bar…”
Most jokes have 2x or 3x of setup. “The priest says…”, “the rabbi says…” which is to establish a pattern of expectancy.
Then the punchline breaks or defies that pattern somehow. Humour is reframing of some sort or another.
The 3x thing seems to be part of human nature.