The forty-minute slip test for arrival day

A compact test for deciding whether an arrival-day route is too fragile for a short trip.

A useful arrival-day test: what breaks if the city arrival slips by forty minutes? If dinner, check-in, prepaid tickets, or a long backtrack becomes stressful, the first route is too tight. If only a cafe stop gets shorter, the plan can probably handle it. This feels more useful than simply adding a generic “two-hour buffer” to every trip.