A boss used to say to us, you haven't proven you know how to do it until you've done it twice. This is, as I recall, also the guy who would pigeonhole people who built things that they couldn't hand off to others. He fed us some bullshit line about being 'too important' to work on the new cool stuff. It was a hard lesson but I learned pretty quick to put extra time in to make my code obvious to others instead of just me. Boost your truck number if you ever want new scenery.
(Most of my coworkers thought he was being sincere in his flattery rather than being ironic. For all I know they are still being 'too important' to work on new subsystems.)
