Wiktionary
experience is the best teacher
prov. Lessons learned from experience are the most lasting.
Usage examples of "experience is the best teacher".
Apparently her instructors had more or less outgrown the notion that experience is the best teacher even though she had been sent to sea while still a child.
Alec, knowing that experience is the best teacher, wisely left her to learn this lesson as she must many another, devoutly hoping that it would not be a hard one.
They say that experience is the best teacher, and let's face it, he's had something over two hundred years of experience.