Nobody is required to find the lesson while still inside the thing. That accounting can wait years, and often does.
What tends to happen is quieter and retroactive. A friend describes a problem and you find you already know the shape of it, because you spent a bad autumn in the same room. You did not study it. You survived in it, and it went in anyway.
Growth is rarely a decision made under pressure. More often it is something you discover you did.