The classic banking change request: regulation X is updated, the policy team rewrites the document, and six months later the new behaviour is live in production. The cost is enormous and the change is small.
Where the months go
They go into translation. Policy to spec. Spec to code. Code to test. Test to deployment. The substance was settled on day one.
A Friday afternoon, instead
The policy owner writes the rule. The system reads it. There is a review, an approval, an audit entry, and a live behaviour by the end of the day.