At a hospital I once worked at, every doctor and department had its favorite software programs. These software programs were located on in-house servers in various departments on several campuses. In the course of my duties, I developed a list of all the programs, their experts, and the location of their servers. I did this mainly for my own benefit, but shared the list with my supervisors, who considered it harmless, but of minor importance.
Then our department was outsourced and my supervisors had to justify their jobs and expenses to their new employer. Suddenly my list became a critical tool for my superiors. “We have to service over 200 programs and 30 servers across 3 campuses! Here’s the list!” was their rallying cry. Documentation helped us all survive the transition.
Moral: Documented work is work you get credit for.