I had some successes but many failures, and generally left a trail of unmaintainable code in my wake as I moved from job to job. It’s not something that I’m particularly proud of. I’ve been contacted by former colleagues, years after leaving a position, to have them tell me that my code is still running every day. When I’ve asked each one of them why, I’ve gotten the same demoralizing answer that has made me regret my implementations: “No one can figure it out to make changes to it, and it’s too important to turn off.”