Indefinite wait seems longer then defined ones, writes David Maiste in his paper “The Psychology of Waiting Lines’, which is why Disney theme parks use complex formulae to calculate and display wait-times. ‘Pre-process’ waits seem longer than ‘in process’ waits, which is why restaurants will seat you before they’re ready to serve you. Customers are happier when queues are acknowledged: when a supermarket calls ‘all staff to the checkouts’, it’s as much about you hearing it as about staffing. And occupied time passes faster than unoccupied time: mirrored walls are especially effective, apparently because most people love looking at themselves.
Excerpt from Help!: How to Become Slightly Happier and Get a Bit More Done by Oliver Burkeman