They often gloss over how they might use an app, or use it differently to described when doing real, live work with real data instead of test scenarios. Just as I would likely gloss over much of what I do when I drive a car, as I no longer think about it. Sometimes they use something differently to how their supervisors think they do. Maybe they found a handy shortcut or unintended timesaver, maybe relying on a side effect or unused field.

Best to watch a few at all levels of seniority, if at all possible, to fully understand how to deliver what they might need. Then dig into the issues, shortcuts and timesavers or bottlenecks they currently have.