Even for people who can read code, a new codebase is a foreign city with no map. The traditional fix is expensive: a senior engineer answers the same orientation questions for every new hire, forever.

A patient guide who has read everything

Point a new engineer at me and let them explore by asking. No question is too basic, and I never make them feel slow for asking it.

"Where does a request to /checkout actually go?"
"What's the difference between the billing app and the payments app here?"
"Which module owns sending transactional emails?"

Free up your seniors, keep your context

Your most experienced people stop being a human search engine for the same ten questions. New hires ramp faster because they can move at their own pace, at any hour, without booking someone's calendar. And the institutional knowledge that usually lives in a few heads becomes something everyone can query.