@Heliograph Thanks for posting that; I feel better about some literary choices. When I wrote my Mars novel I decided to use a single universal time for the entire planet. People can't live on the surface and most development is underground for radiation reasons. No windows. Some population is on spaceships or a station. One zone gives the same diurnal schedule to everyone everywhere. When they rarely need to use the surface, they use offset and solar terms, "like local dusk is just before lunch."