Mean cycle time

One number with a long-tail problem

The mean is easy to calculate and useful for some capacity models. It is sensitive to unusually long cycles, however. If most items finish quickly while a few wait weeks, the average may describe no actual item in the system.

A concrete example

Suppose five illustrative changes take 2, 3, 3, 4, and 18 days. Their mean cycle time is 6 days, while four of five finish in four days or less. Looking only at six days would hide the long-running change that deserves investigation.

Use it with the distribution

Report the item count, time window, exclusions, and workflow boundaries. Compare the mean with a median and high percentile, then inspect the tail. If the work mix changes, segment before interpreting a trend.

Limitations

Mean cycle time is not a service guarantee and does not reveal causation. It can fall when difficult work is excluded or when items are split. Keep the calculation stable and pair it with examples.