Which Signal Should Make a Team Change Its Plan?

A scenario is useful only if it helps a team notice when its assumptions no longer fit. But choosing a signal to watch is harder than listing possible futures: a metric may move for several reasons, and waiting for certainty can make the response less useful.

When planning under uncertainty, what evidence should trigger a team to revisit its plan—a measurable threshold, a repeated pattern across sources, or a change in the underlying assumption? And who should be responsible for deciding whether that signal is strong enough to act on?