Time and Calendars

Some of the fan produced material, especially "The Verse in Numbers", spends a lot of time trying to make everything be equal to Earth: length of days, length of seasons, gravity, etc. They come up with some ideas which are rather outlandish to me.

Instead, I say "It's science fiction, these are different planets, things should BE different!"

So, I say life is pretty adaptable. If you live on a colony world with a 20 hour day, you get used to it, you make changes. If your planet's year is twice as long as Earth's, then you genetically engineer your crops so you can get in two growing seasons each year. Maybe you live on a planet with very little seasonal variation. For example, if Earth's axis of rotation was perpendicular to its orbital plane, there would be almost no seasons anyway.

As far as human time tracking, the Alliance uses Earth's standard 60 minute hour. A "day" would probably be the length of Londinium's day or might be Earth's standard 24 hour day. Standard time would be like Greenwich time is on Earth. A digital watch would be able to convert from standard time to local time as would any computer or electronic device. There might be a local calendar for seasons, but dates would use the standard calendar, so Unification Day is the same day on every world.
If the planet's local year is three Earth years long, then sometimes Christmas is in the summer, sometimes its in the winter.

Different planets would have a local clock divided into normal hours and maybe an adjusting hour at midnight. So on a planet with a 20 hour 37 minute day, the equivalent hour from Midnight to one AM would only be 37 minutes long.

On poor rim worlds, people might not care. You get up when the sun does and work the fields until dark and go to bed. They might use the local calendar all the time and only refer to official, "standard" time for things like births, etc. Maybe the one thing that everyone on the Rim has is a digital clock/calendar. Maybe really poor towns just have one that the Mayor keeps for recording events.