Using the formulas of queuing theory everyday waiting situations can be examined. Exemplary the following 4 models are considered:

- There are two operators available. The arriving customers are assigned by a so-called dispatcher to the next available operator. This principle is used at the check-in at the airport for example.
- Here are two parallel servers available, too. But the clients are divided 50%/50% to the two queues at the time of arrival.
- There is only one operator and one queue. But the operator can serve two customers simultaneously.
- There is only one operator and one queue. But the operator works at double speed.

In case (b) we have assumed that the half of the arriving clients will be assigend to the first queue and the other half to the second queue. Choosing the shorter queue does not take place. On the page Queueing system with control we describe how a queuing system can be improved by just such measures.