Queues are inevitable in product development processes but can be managed and constrained to reduce economic waste. The goal should be to reduce congestion like managing traffic flow on a freeway rather than maximizing utilization like a parking lot. Measuring and modeling queues can help highlight where handoffs and wait states undermine performance. When queues start to grow, quick interventions may include limiting new commitments, adjusting staffing levels, changing the work mix, or applying efforts to reduce the queue. Everything flows, so adaptive management of queues is important to maintain flow in business processes.

1. https://www.videvo.net/video/timelapse-of-traffic-in-downtown-hong-kong/7914/
PA U L R AY N E R
@thepaulrayner
F I G H T I N G T H E
I N V I S I B L E E N E M Y

2. “…the enemy of flow is __________?.”

3. – J O H N N Y A P P L E S E E D
“Type a quote here.”

4. – D O N R E I N E RT S E N
“…the enemy of flow is the invisible and
unmeasured queues that undermine all aspects
of product development performance.”

5. Development queues are invisible
MODEL THEM

6. EventStorm your value flow
Highlight queues (i.e. handoffs/wait-states)

7. Measuring and managing queues with Flow
flow.virtualgenius.com

8. Time for a metaphor

9. Is team capacity a PARKING LOT?

10. https://upload.wikimedia.org/wikipedia/commons/thumb/9/91/Cedar_Point_parking_lot.jpg/1024px-Cedar_Point_parking_lot.jpg

11. Team capacity is a parking lot
TEAM CAPACITY IS A FREEWAY

13. Many teams operate in a state of
continuously high congestion

14. – J O H N N Y A P P L E S E E D
“Type a quote here.”

15. https://blog.danslimmon.com/tag/queueing-theory/

16. https://blog.danslimmon.com/tag/queueing-theory/

17. https://www.flickr.com/photos/volvob12b/9580811408
High congestion ==> Parking lot
https://www.flickr.com/photos/volvob12b/9580811408/

18. If you are a PARKING LOT
your goal is to MAXIMIZE UTILIZATION
If you are a FREEWAY
your goal is to REDUCE CONGESTION

19. Queues are emergent phenomena

20. Queues are emergent phenomena

21. Queues are inevitable

23. Queues increase cycle time nonlinearly

24. https://blog.danslimmon.com/tag/queueing-theory/

25. Queues grow faster than we can
shrink them

27. https://blog.danslimmon.com/tag/queueing-theory/
S W E E T
S P O T

28. Queues are a leading indicator of
longer cycle times and reduced
throughput

29. – R E I N E RT S E N
“Queues are the root cause of the majority of
economic waste in product development”

30. The goal is NOT to eliminate all queues
The goal is to
MANAGE AND CONSTRAIN QUEUES
(i.e. reduce their economic cost)

31. Reduce batch size
(e.g. slice your stories) to reduce
queue size

32. – R E I N E RT S E N

33. Make quick, forceful interventions
when queues start to grow

34. “The real art of managing queues is not about
monitoring them and setting limits, it’s
WHAT WE DO WHEN WE REACH THE LIMITS”
– A D A P T E D F R O M R E I N E RT S E N

35. 9 ways to deal with emergent queues
1. Block making new commitments
2. Purge low-value commitments
3. Shed functionality
4. Quickly apply effort to the queue
5. Part-timers
6. Specialists
7. T-shaped people
8. Cross-train at adjacent processes
9. Change the job mix
DEMAND-
BASED
SUPPLY-
BASED
CLEVER!

36. – H E R A C L I T U S
πάντα ῥεῖ

37. – H E R A C L I T U S
“Everything flows”

38. T H A N K S
Paul Rayner
@thepaulrayner
paul@virtualgenius.com
exploreddd.com