Experience is what gets you through a test. Revision/studying etc are giving you more experience in doing something. Therefore, if you make a mistake, you learn from it (experience)... Hence the sig. Thats how I understand the sig anyway...
I'm sorry if this sounds like an attack, but what you said couldn't be more wrong.
Experience doesn't get you through a test - knowledge does.
Studying gives you that knowledge.
Experience comes from actually doing something, so after you would have been tested, you would have experience.
Now, saying that you learn from a mistake is fine. But learning does NOT equal experience.