Notes

Queue capacity utilization is the amount of time the service process is working (not idle).

Knowing capacity utilization allows you to predict many characteristics of a queue.

Percent capacity utilization and percent queue time are identical for a random queue.
 If you operate an $M/M/1/\infty$ queue at $X$ percent utilization, you're choosing to use $X$ percent queue time.

Queues grow when you approach 100 percent utilization, they become exponentially large.

It's hard to measure capacity utilization directly.
References
Backlinks
 The Principles of Product Development Flow
 Capacity Utilization Increases Queues Exponentially
 DemandFocused Approaches to Control WIP
 Effects of Set a Limit on WIP (Work in Process)
 Enhance the Effectiveness of WIP Constraints by CrossTraining Workers
 HighStates/Congested Queues
 Kanban Pull Principle
 Most of the Damage Done by a Queue Is Caused by HighQueues States
 Queue Capacity Utilization Allows You to Predict Many Queues Characteristics
 Slack and Queue Capacity Utilization Are Correlated
 Theory of Constraints (TOC)  Elevating the Constraint
 When Response Time Is Important, Measure Response Time
 Work in Process (WIP)