A good teacher shortens roads they once had to walk the long way.

A teacher’s real gift is not information, it is compression of time. They have already taken the wrong turn, spent the wasted year, learned which of the obvious approaches does not work. Handing that over lets someone arrive in months where you arrived in years, and it costs the teacher nothing they still need.

If you know something well, ask what part of your route was avoidable. That is the part worth giving away. Say it plainly to someone earlier on the same road.