What is bottleneck?

Waiting time is measured between steps, not inside them. A step that takes two minutes to perform but sits four days in someone's queue is a four-day bottleneck. Making the rest of the process faster changes nothing until that queue moves.

Four steps on one order-to-cash process, ranked two ways.

By duration alone payment wins on 41 days. By cash-days held it still wins — but client review closes most of the gap, and it is the one you can act on without asking the client for anything.

Effort spent anywhere other than the bottleneck produces no improvement at all. It is the one place where a week of work returns a week of cash.

The longest wait is not always the most expensive one. A step that holds ten cases for thirty days matters less than one holding four hundred for six. Rank bottlenecks by total value held, not by duration, or you will fix the slow step that no money passes through.

Measuring work time instead of wait time

A certification that takes forty minutes of effort and sits four days in a queue is a four-day bottleneck. Timesheets and effort estimates measure the forty minutes and miss the process entirely.

Fixing downstream of the constraint

Speeding up any step other than the bottleneck adds nothing to the end-to-end time. It usually just grows the queue at the bottleneck faster.

Reading the mean

One case abandoned for a year drags the average and tells you nothing about the typical case. Read the median and the P80 together.

Crestline measures the wait between steps rather than the time inside them, then ranks by cash held × days rather than by days, so the list opens on the step where a week of work returns the most cash.