This type of perspective is common. In fact, computing systems are actually composed of a series of interconnected queuing systems. This is called a networked queuing system. An Oracle transaction does not really enter a single large system, wait to be serviced, is serviced, and then exits to return the result. It enters a complex series of queuing systems, moving from one system to the next, each with the possibility of queuing and then servicing the transaction. When the transaction exits the complete system, the sum of all the service time and the sum of all the queue times are presented as simply the service time and the queue time. So, this type of abstraction is very common.

* It allows our performance analysis to move forward without insignificant details getting in the way of the problem at hand. Our goal should always be to keep situations as simple as practically possible. Added complexity and precision take effort and resources that should not be expended unless absolutely necessary.

* All time is accounted for; that is, time is not lost or unaccounted for. It is simply classified in an abstracted and summarized format.