Checklist
Separate touch time from queue time
Elapsed time contains different levers.
When it fits
- When a task feels 'slow' but nobody knows whether work itself or waiting dominates.
When to avoid it
- Queueing equations have specific assumptions. Use them for directional reasoning and measurement design, not as exact forecasts for arbitrary multi-stage knowledge work.
Checklist
- Timestamp start and finish.
- Estimate active touch time.
- Classify major waiting intervals.
- Measure rework separately.
Why it matters
For a sample of items, split active processing, waiting for people, waiting for systems and rework. Target the largest controllable component instead of speeding every step.
An example
A change takes five days elapsed but only ninety minutes of active work; approval and environment waits dominate.
Check your result
The improvement target corresponds to the largest material time component.
Keep this limit in mind
- Queueing equations have specific assumptions. Use them for directional reasoning and measurement design, not as exact forecasts for arbitrary multi-stage knowledge work.
Connected ideas
Useful withReduce batch size when feedback delay dominates
Evidence and sources
Supports
Little's Law relates long-run average work in a stable system to arrival/throughput rate and average time in system as L = λW under stated mathematical conditions.
The relation does not identify root cause, queue discipline or the correct intervention; workplace applications must respect the assumptions.
A Proof for the Queuing Formula: L = λW · Abstract