Why we are better off monitor our queues

The other (not so obvious!) way is to look at the size of the queue in front of the process. Because if we know the work time and queue size, we can derive the rest.

Cycle time measurement

Apart from this, the queue can tell us a lot more which cycle time necessary don’t:

  • If we have a bottleneck our system
  • Disruptive flows such as bursts in arrival of work

The queues are simple easy visual ways of learning us about variance in our system. And variance eats predictability for breakfast.

The same fact is actually mathimatically demonstrated in Little’s Law:

Little's law

Number of things in process = sum of items in queue and process. So by eliminating the queues we get a faster cycle time.


  • cycle time is a trailing indicator
  • queue utilization is a leading indicator

Unfortunately, we very seldom in monitor the latter!

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