Every operation makes exceptions. Very few can say how many, of what kind, or who made them.
Why it matters
An exception without a reason is invisible by the next morning. Thirty of them a week look like normal work. With a code attached, the same thirty become a list — and the list usually has one entry at the top with half the volume, which is the thing worth fixing.
Codes also change the conversation. “Stop doing exceptions” is an instruction nobody can follow. “Exact-time requests from one sales channel account for 60% of our exceptions” is a decision somebody can make.
How you notice it slipping
The free-text note is used instead of the code, so nothing can be counted. There are twenty codes, which means people pick whichever is nearest. Or there is one code called Other, which is where everything goes.
What to do
Keep the list short — five or six codes that describe genuinely different causes — and review the counts weekly, not the individual notes. The point is never to punish the exception. It is to find the upstream rule that keeps producing it.