Star Wars never really explores the cool time-keeping situations that you can end up with in a society that spans multiple planets: 

  • planets with no moon that don’t have a time increment between days and years
  • planets with a dozen moons where understanding their cycles involves university courses
  • multi-planet star systems where the position of the other planet features prominently in calendar systems
  • tidally locked planets with no days (or years, really, because even though they’re orbiting a star they wouldn’t have significant changes in seasons)
  • and not only do they not have days or years, they have no cultural concept of those things and are bewildered by the rest of the galaxy’s obsession with measuring time
  • planets with years so long that they’re useless as a way of measuring age, so people give their age in months instead
  • planets with like 6 hour days where people are used to sleeping frequently for only a couple hours at a time
  • the space equivalent of jetlag involves adjusting to a new day length, not just a new time zone
  • when two planets have slightly different day lengths, the days shift relative to each other, so if you travel frequently between two such planets, sometimes the days line up perfectly and sometimes you have to deal with 12 hours of “jet”lag

And there are tons of interesting cultural implications that go along with using Coruscant time as a standard throughout the galaxy:

  • standard Coruscant dates have basically no correlation to seasons on planets with different year lengths, so to even guess at the weather during a historical date given in standard time you need to do calculations
  • everyone has a different age in local years and standard years, and a different birthday
  • some planets have days much longer or shorter than standard days, so your standard birthday might be spread over a few local days or vice versa
  • stuff like being old enough to drive – it tends to go in round numbers of local years, so even on planets where the rule is “about 18 standard”, you have some planets where it’s actually 17.36 standard years, or 19.1, or whatever works out nicely in local years
  • planets that follow Coruscant standard time and totally ignore natural phenomena on their own planets
  • up to and including days – they force themselves into sleep cycles with nothing to do with the sun rising and setting
  • planets that refuse to use standard time even in official settings, and pilots hate having to travel there because the space port is always chaotic because no one knows what time it is
  • the Separatists try to switch to another time system than Coruscant standard and it’s a total mess but it would be embarrassing to switch back
  • the Rebellion learns their lesson from this and doesn’t try to change the standard time system even though the New Republic government is no longer based on Coruscant
  • people pay less and less attention to standard time as you get farther from the core
  • planets with similar natural time cycles to Coruscant have more prosperous economies and produce more prominent and successful people, although the effect is subtle enough that it goes unnoticed until someone randomly decides to check for correlation