Followup to: The Most Important Thing You Learned
What's the most frequently useful thing you've learned on OB - not the most memorable or most valuable, but the thing you use most often? What influences your behavior, factors in more than one decision? Please give a concrete example if you can. This isn't limited to archetypally "mundane" activities: if your daily life involves difficult research or arguing with philosophers, go ahead and describe that too.
The most frequently useful is map and territory. It is something that I deploy on a daily level to remind myself of the value of never believing that I know everything, and to leave myself open constantly to the possibility of making mistakes and updating my beliefs. It is also one of the most basic things I teach at Intentional Insights.