Why does kill criteria fail?

The most common reason kill criteria fails: Setting kill criteria so vague they never trigger ('if things aren't going well') or so extreme they're functionally irrelevant ('if we lose all our customers'). Useful kill criteria live in the uncomfortable middle — specific enough to fire, realistic enough to actually happen. The other failure mode is setting them and then renegotiating when they trigger. If you move the goalposts every time the ball approaches, you don't have criteria — you have theater.

The fix: Pick one active project, commitment, or investment you're currently pursuing. Write down three specific, measurable conditions under which you would abandon it. Be concrete: a date, a number, a threshold. Now show them to someone else and ask: 'Would you hold me to these?' The discomfort you feel is the exact discomfort kill criteria are designed to bypass.

The underlying principle is straightforward: Define in advance what evidence would cause you to abandon a course of action.