What is a Lead Time?
Lead time is the clock the customer sees: from the moment work is requested to the moment it's delivered — queue time included. That inclusion is the point: most delay in most systems is waiting, not working, and lead time is the metric that refuses to hide it.
Track its trend and distribution ("85% of items ship within 9 days") rather than averages alone; the tail is where the broken promises live.
Formula
Lead time = time from request to delivery (cycle time + waiting)
Worked example
A marketing team promises "creative requests done in a week." Data shows the design work itself takes a day — but requests wait six days in an intake queue behind a weekly triage meeting. Moving triage to daily drops lead time from 7 days to 2 without anyone designing a single pixel faster.