I recognize this will vary depending on how much you self-host, so I’m curious about the range of experiences from the few self-hosted things to the many self-hosted things.
Also how might you compare it to other maintenance of your other online systems (e.g. personal computer/phone/etc.)?
A bit of both. It really depends on the game. Some games are super simple, just launch an executable and hand out the IP. Others are needlessly complicated or just horribly coded. My example game is just an absolute mess all around even just as a player; running a server is no different. And since the actual game is all user-made, sometimes the problem is the server software, and sometimes it’s how the mission you’re running was coded. Sometimes it’s both.