We have run engagements in every shape imaginable since 2018. Six-week scopes that drifted into ten. Open-ended retainers that turned into furniture. One-week experiments that left no time to recover. Two-week sprints are not a clever methodology choice — they are the only shape that did not fall apart after a year of use.
A sprint of less than two weeks does not leave room for the second-week course correction. By the time you have learned what is hard, you are shipping. A sprint of more than two weeks does not get the mid-sprint Friday demo — and without that demo, the original scope drifts unchallenged.
Two weeks is also a length the client can hold in their head. They know the demo date. They know who is on it. They know what is being shown. The cognitive load is lower for them than for us — which is the right way around for a service business.
There is no clever finish. We just keep doing it. After 184 sprints we have not yet been asked to abandon the unit. Most clients have asked us to schedule the next sprint before the current one is over.