Goldilocks enters the house where THREE bears live, and she tries THREE things inside (food, chairs, and beds). This might be the classic story that more clearly uses the "rule of three"
This is day 17 of #BetterStories
We'll see plenty of examples
How can you use the rule of 3? When you want to give rhythm to the story
Don't use fewer, because they wouldn't be enough to develop the situation. Don't use more, because three are sufficient and more don't really add anything new