What number in your business are you trusting without having checked it lately?

There is a number in each of my businesses I trust without actually checking it lately, a margin, a churn count, a client total. I tell myself it is probably still fine because it was fine the last time I looked. The problem is I cannot remember exactly when that was. Curious what your version of that number is, the one you feel most confident about without having actually looked at it recently, and whether you have ever been wrong about it.