Excerpt (edited) from You Can’t Learn from Failure, You Can Only Learn from Success by Jerry Neuman:
Any complicated system is too complicated to learn from failure. Yes, you can learn a few tricks, like: “don’t spend all your money on fancy chairs” or “don’t hire your college drinking buddies as EVPs of Business Development.” But all you can learn from failure is to avoid that particular kind of failure. And so what? There are too many other kinds of failure for that to make any difference. You need to learn from success. You should be spending your time trying to learn from success.
The successful entrepreneurs I have known have had the ability to look at a failure, any failure, and pull out the couple of things that were done right. These are what they focused on.
If you’re going to learn from failure you need to learn how to avoid every possible way you can fail. It’s a waste of your time. You only need to learn one way to succeed.