There's normally a list of things I could have messed up, e.g. poor English, no visa, wrong time zone, sloppy code, too slow on a certain test, many other great

There's normally a list of things I could have messed up, e.g. poor English, no visa, wrong time zone, sloppy code, too slow on a certain test, many other great applications, poor understanding of a framework, etc. You can trace back a one sentence comment to the actual root cause. It's like debugging. And from that, you spot the pattern and optimize.