Flow and pull
Work moves faster in small, steady streams than in big batches. Less work in progress means shorter waits for everyone.
About 5 minutes to read.
Key idea
Imagine a café where the barista takes ten orders, then makes ten coffees. The tenth customer waits for nine other drinks, and the first customer’s coffee cools while the others are made. Now imagine the barista making each coffee as it is ordered. The work is the same, yet everyone waits less. That is flow.
There is a tidy relationship behind this, known as Little’s Law: on average, lead time equals the amount of work in progress divided by the rate at which work is finished. If a team finishes fifty claims a day and has five hundred in the system, a new claim waits about ten days. Halve the pile and, with the same effort, the wait halves too.
Pull means starting new work only when there is capacity to finish it, rather than pushing everything in at the front and hoping. Simple signals, such as a limit on how many items may sit in each column of a board, stop the piles growing again.
Example: insurance claims
The weekly batch
An insurer’s claims team sorts the post once a week, so every claim waits for sorting day. The handlers then each take a bundle of forty. A simple claim at the bottom of a bundle waits for thirty-nine others before anyone reads it.
Sorting daily and taking claims one at a time from a shared queue, simplest first, cut the typical wait from twelve days to five in this example, with the same people and the same hours.
Warning signs
- Big piles of part-finished work between teams.
- Weekly or monthly runs that set the pace for everything else.
- Everyone is busy, and the work still moves slowly.