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Exception
The case the process did not anticipate.
Ordinary work is mostly routine with a tail of oddities: the duplicate, the overdue-but-explained, the customer who is technically ineligible and obviously should be helped. The routine part automates easily. The tail is where the judgment lives, and it is usually a much larger fraction of the work than anyone expects.
Why it matters
Demos show the happy path. Operations are mostly the tail.