OPS.10.1:2 - Problem

Dividing mean demand by nominal capacity suppresses the arrangement that makes service possible. It can hide shared attention, interrupted availability, burst arrivals and visits that fail to produce a final result. A mean waiting-time formula can then be used to promise a deadline it never calculated.

At the other extreme, a full simulation can consume effort while leaving a simpler decisive bound unused. The difficulty is to model enough of the service process to answer the question and identify which assumption or relation needs revision when the model is insufficient.