The person learning a system is testing the clarity its designers have stopped questioning.

Familiarity destroys your ability to see your own work. After enough time inside a process, the confusing parts stop registering, because you navigate them from memory rather than from the instructions. A newcomer is the only reliable instrument available, and the window is short, since within weeks they will have absorbed the same assumptions and stopped noticing too. Their confusion is data with an expiry date.

Ask whoever joined most recently what made no sense in their first fortnight, and write the answers down. Fixing even two of those items helps far more people than the one who reported them.