Code rage

In line with my third further goal mentioned below (adding counter to frame to show time remianing of buff), I've searched through a number of addons for system timer callback registration functions. My theory is that since several addons seem to provide stopwatches, time counters, that sort of thing, there must be an API call to register a callback/listener for a time event on some regular basis, say x ms or so.

If there were no such thing, addons would have to rely on other events firing frequently enough to make a smooth and accurate timer. Which would be silly, ofc. So, there must be an API call, and altho I have gone through several addons and not found it, I must've just missed the relevant line of code due to drunkenness or hübris, right?

Right?

I've gone through several addons now, and I just can't seem to find a call to some "system" library providing callback functionality based on time. It's ridiculous. Even in files named CoreTimerHandling.lua, or such, have I had much luck. It is crazy, crazy, and I'll go crazy, too, soon. I mean it just CAN'T be that everything relies on frequent enough events of other types. It's not clean.

I'll have to check some more.