How do we train people for exceptions the instruction sheet does not cover?
Teach people why a workflow step exists, and they can spot when an unfamiliar case needs the same care. Confirming the current source protects against using an outdated policy, for example, and confirming the recipient protects against involving the wrong person.
A checklist covers the familiar case. Pick one important check and explain the consequence it prevents, then show an ordinary example next to an exception. Then ask the learner which fact matters and where they'd verify it, and let them explain the reasoning in their own words.
Keep the explanation inside the person's role. They should know when to ask for help. Nobody needs to become a legal, security or technical specialist for every case.
I'd use feedback from real work to keep updating the examples. A maintained set of reasons and cases can serve people better than a growing list of isolated warnings. That way a person learns the boundary well enough to spot it when the surface details change.
What to try this week
Take one check in your AI workflow and write down the consequence it prevents. Run it past a colleague who hasn't seen the sheet and see whether they can name the fact to verify.