Cashier is open 1 channel lengthy queues when customers start and are paid at the Cashier is having problems, you should hurry to add, not wait until a customer solution and leave customers waiting in queue .
Cashier is open on one channel that customers have long queues. Are paid at the Cashier and customers are having problems, it should quickly be added. Not wait until the complete customer solution. And leave customers waiting in the queue.
Cashier open 1 channel when the client starts long queue And the customer's payment in Cashier has problems it should not wait for the problem to increase the customer. And let customers waiting in the queue!