The Rule of Three

Interesting advice from Harvard Business Review:

APRIL 6, 2010
Know When to Confront Someone
When someone shows up late to a meeting or makes a comment that makes you uncomfortable, it can be difficult to decide if it's a big enough deal to address or if you should let it go. In situations like these, try using the "rule of three." The first time someone does something that makes you uncomfortable, take notice of your discomfort. The second time, acknowledge that the first time was not an isolated incident and that there may be a pattern emerging. The third time it's time to speak up. Tell the person that you've noticed something three times and you want to discuss it with him. This simple rule can both help you determine what's worth raising and hold you back from jumping on every single issue.
[Text from Harvard Business Review: Management Tip of the Day (email)]

There are some interesting comments on the main article (puppy pee theory, additional analysis, caveats, etc.). Regardless of the form it takes, I think I like the idea of having personal rules with how to deal with different situations. What do you think?