I have a student who works in comedy, and we recently had a nice conversation about the rule of threes.
The essence of the rule is that any slogan, a joke, or a story built in three parts has the greatest impact.
The standard breakdown of the rule is:
You set up the joke, you reinforce it by either reminding us of the central premise or by building on it, and then paying it off by either delivering the punchline or disrupting the expectation.
This rule not only works in comedy, but almost any genre, including horror and action. As an example of this, watch this excellent breakdown from Lindsay Ellis of setup, reinforcement, and payoff in Mad Max: Fury Road (a genre film that continues to make me marvel in its craftsmanship).
In his book, Impro, Keith Johnstone says that an improviser “shouldn’t really think of making up stories, but of _interrupting routines._”
The rule of threes works similarly. The first part sets up the basis, the second one reinforces it, and the third one disrupts it.
To be clear, we don’t need routine to mean without conflict.
I often rail against people who spend time “setting up” their story, when in fact, they should be establishing how their characters are in conflict—most often internally.
Before the story begins, characters want something they believe will make them feel fulfilled, or they seek to deal with the internal obstacle or flaw that stands in their way of that fulfillment.
Our job as writers is to show the routine of that conflict through action.
Once we’ve shown the routine of conflict, we can now disrupt it.
This often occurs through external stimulus because the character has been stuck so long in this static conflict that they can’t internally solve the problem. A disruption is required.
But once it does occur, the real story, the story our readers signed up for, begins.