You reworded my comment.

edit. You've lost your keys. You look in your pants pocket 500 times. Insanity, because you're doing the same thing and expecting that this time the keys will show up, even though they weren't there the first 499 times.

You play "O, Canada" on the steel drums 500 times. Sometimes you play it through perfectly and occasionally you make a mistake. You note the mistakes. When you play it right you're getting the result you expect, and if you make a mistake, you adjust.