The new employee notices the instructions hidden inside everybody else’s familiarity.

A newcomer is briefly able to see what everyone else has stopped seeing. The steps nobody writes down, the exception everybody knows about, the form that is always filled in wrongly on purpose: these are invisible to people who have absorbed them and glaringly obvious to somebody on their second week. That clarity has a short life and is rarely collected before it disappears.

Ask new people to write down everything that confused them in the first month, and mean it. Thank them for the awkward questions rather than answering them briskly. Within a few weeks they will be as blind as the rest of you.