You ever write a block of code, but instead of running the code through your mind to see if the if-then-else statements make sense, you just say "fuck, let's run it anyways" without checking?
Actually, the better question is, do you ever NOT do this?
Sometimes when it's cheaper to try and run to see the results.
Best results are achieved when one has a complete understanding of what they are doing.
It's also what you do when you're first learning something.