The waiting list a busy front desk actually runs on

Two staff calling the next customer in the same second is the Saturday-afternoon case, not an edge case. The claim happens in one write, so one of them gets that customer and the other gets the following one — instead of both walking out to the waiting room for the same person.

Twenty minutes told at the door and forty minutes actually waited is the gap a customer judges you on, so both numbers are kept. A system that quietly re-quotes as the queue grows always looks accurate and teaches you nothing.

A customer who leaves is the clearest signal a shop has about its own capacity, and it is invisible in takings — they simply never appear. Recording it turns a bad Saturday into something you can staff differently.