[kahnix]

While the rest of what you said is true, perpetual calendars require setting for the year 2100, still a while to go though!

[cge]

The article points out some mechanisms that account for that.

However, at that time scale, I have to wonder whether the mechanism can, or should, run for over a century without stopping, which would seem to imply running without being cleaned or serviced beyond a certain point.