Have you ever had to do a knowledge transfer. I just did. All the work for the past 4 years compressed into a couple hour meetings.
Sure I've tried to document most of my work, but there are so many things one picks up over the years which you know but you don't think of at the time.
That is why, going forward, I'm going to try a little bit harder on documenting things.
And always have a backup person for what you do. Because as the old saying goes, you could get hit by a beer truck.
And make sure your supervisor knows what exactly it is you do, even if they are not technical.
Because once that resource is gone, that's when the mystery begins.