You could do a clock app for that, but you'll still have to deal with 'official' time and dates for so many things. Mind you, I can tell you it can be a pain to support computer systems when the clocks change. Calculating dates is hard too.

Here we are working with 60 minute hours that link back to the Babylonians, days named by vikings, months named by Romans and trying to make it all work with computers. During the French revolution they tried using 10 hour days that had 100 minutes. That would have been simpler for computers. People have messed with this stuff forever.