What is the system administration equivalent to dogfooding?

I don't think there'll be as clear an answer as for programming, but a couple partial answers come to mind:

Using a PC that's set up from a standard image the same as anyone else.

Running with user privs. most of the time, elevating only when necessary.

Another thought: Ask a close friend or relative to go through your documentation and follow it and tell you honestly if it's clear.

Place the same trust in your backup system that your users do, and delete your home folder. If that sounds scary, or if you think it'll take too long to recover, maybe you need to improve your backup system.