The cost of a hidden rule.

Name the business choice

A special case can begin as a reasonable shortcut and gradually become a business rule. I would look closely when someone says a value must always be changed by hand or that a particular record should be ignored. The explanation often matters more than the code that implements it.

I want the rule to have a name, a reason, and an owner who can revisit it. That makes future changes easier to discuss. It also helps distinguish a lasting policy from a temporary accommodation whose original conditions may no longer apply.