The Overwhelmed Gatekeeper

A city's gatekeeper was instructed to check every traveler's papers thoroughly.

On quiet days, this worked well.

On market day, a hundred travelers arrived at once. The gatekeeper, trying to check all papers thoroughly, created a line that stretched a mile.

Merchants missed the market. Tempers flared. Fights broke out.

A new policy emerged: on busy days, check papers quickly. Let some risk through rather than create chaos at the gates.