Efficiency · 03 / 07
Utilization curve (Kingman)
When a team works close to 100% of its capacity, the wait for whatever reaches it does not grow in a straight line: it shoots up. Variability in requests and in the work multiplies the effect.
wait ≈ ρ / (1 − ρ) · (cₐ² + cₛ²) / 2 · tₛ
Try it
Raise the team’s utilization little by little and see how long requests wait in its queue.
- Measured average wait
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- Wait according to the formula
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- Average queue
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- Formula vs 70%
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Where it applies
- A platform team planned at 100% keeps the other teams waiting weeks for every request.
- Hospital emergency departments break down above 85–90% bed occupancy.
- An approval committee that meets every week with a full agenda piles up pending decisions for months.
Where it comes from
John F. C. Kingman, “The single server queue in heavy traffic” (Proceedings of the Cambridge Philosophical Society, 1961). Hopp and Spearman brought it to management in “Factory Physics” (1996), and Donald Reinertsen to product development in “The Principles of Product Development Flow” (2009).
Bring it to your organization
In my workshops and diagnoses we work on this and other principles over your team’s real flow of work, with your data rather than the simulation’s. See services or write to me.