For me it's between inferential distance and cached thoughts, at least for ones I explain to other people. For ones I use myself, Line of Retreat is probably the one I actively pursue most frequently.
Though I end up using Absence of Evidence pretty often as well.
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.