[joezydeco]

The biggest queue problem I see in a large store is McDonald's.

In the early days, the food was all built asynchronously from the orders. Cashiers would walk back and fill the order themselves from the bin full of burgers and fries in pretty quick fashion and the customer would be on their way.

When the whole "made as you go" approach was started, McDs decided to keep the 1:1 cashier-customer model (unlike Burger King or Wendy's, who do it 1:N style).

So now you have customers ordering and standing around next to their cashier waiting for the food to be made, which the cashier has no control over. The order of filled requests is also somewhat random. If the kitchen is having trouble, people start piling up by the counter.

I've noticed that some stores are experimenting with a numbering system that is encouraging you to step back and watch a monitor for your order when it is ready.