here's a dumbed down version of what I did a while back for one of my projects where I needed a way to schedule tasks similar to the linux cron daemon. I had issues with timers and it randomly not triggering exactly on the second, It tended to vary from 00-02 at the maximum (although I do believe I rarely saw a :59 as well), so I used a multimedia timer, factoring in system ticks to derive the offset to get precisely on the second for every minute.

a cron job in linux starts with 5 tokenized positions, a command, and an optional output
[a] [b] [c] [d] [e] [command] [output]

Code
[a] - Minute 
[b] - Hour
[c] - Day
[d] - Month
[e] - Day of the Week


I wound up just tokenizing $asctime($ctime,n H d m ddd) so I could have minutes, hours (24), index of the day of the month, index of the month, and a 3 character representation of the day name, Sun,Mon,Tue.... Which gave me practically the same information to work with as a cron job, although I had to figure out evaluating rules to really mimic a cron daemon such as intervals "/" and ranges N-N, amongst other special characters like " * and , ".

If you're interested I can post the finalized project, but for sake of demonstration, this is HIGHLY stripped down just to demonstrate the execution perfectly on the minute.
Although this doesn't adjust for your situations like timezone swaps and daylight savings times, but it shouldn't be too messy to incorporate this.

To try it out, just use /crond

Code
alias crond { .timerCrond -ioh 0 1 crond.signal 1 }
alias -l crond.offset { return $calc((60 - (($ctime - $ticks / 1000) % 60) % 60) * 1000) }
alias -l crond.signal { if ($round($calc(($ticks / 1000) % 60),1) == 0) { .timerCrondSignal -h 1 $crond.offset .signal -n CRON } }
on *:SIGNAL:CRON: { echo -s Time Event: $asctime($ctime,hh:nn:ss tt) }


Result after running for some time (13 minutes):
Code
Time Event: 03:07:00 pm
Time Event: 03:08:00 pm
Time Event: 03:09:00 pm
Time Event: 03:10:00 pm
Time Event: 03:11:00 pm
Time Event: 03:12:00 pm
Time Event: 03:13:00 pm
Time Event: 03:14:00 pm
Time Event: 03:15:00 pm
Time Event: 03:16:00 pm
Time Event: 03:17:00 pm
Time Event: 03:18:00 pm
Time Event: 03:19:00 pm


Perfect execution on the minute! It may seem a bit excessive to use a multimedia timer on such a fast interval, but since it hardly does anything, it really isn't a performance hit, least none that I see on my system. Always signals exactly at a minute change, so effectively no adaptation would be needed within the code, only the signal event to handle your edge cases like moving timezones and daylight savings time adjustments. The signal event is where you'd want to code for your timed events anyways rather than setting a timer.

I use this for all sorts of nice things, like echoing day changes to all channel and query windows so I don't have that awkward instance of replying to a message at [xx:xx] coming to find out that it was a day or two ago at exactly that time, and no activity was within that window to indicate otherwise lol.

I also do it for scheduled maintenance and saving of various hash tables. There's a lot of usefulness to this and is robust much like your feature request. I hope it helps!