Why do we have leap years? It's a way of allowing for the fact that the Earth does not, in fact, orbit the sun in an even number of days. (We also have occasional leap seconds that only those keeping the most precise time need to worry about. If you sync your computer clock to an internet time server, they happen automatically for you).
When we think about other planets, we acknowledge that they will have to have different calendars. Whether these calendars are invented by natives or colonists from Earth, what are the chances that any planet's year will be evenly divisible by its day? Pretty slim. Another planet may have leap days every five years, or two, or ten. It's not something I've ever seen mentioned in fiction. And given the Romans invented leap years, you don't need what we would consider an 'advanced' society to realize the necessity (although a fantasy society may also use a purely lunar calendar and ignore the solar year except for planting...and a society that lives in the tropics is very likely to worry only about the lunar year. If you don't have seasons, the solar year becomes completely irrelevant).
What kind of calendars are used on your other worlds. And if humans have spread out into the stars, what kind of calendars do starships use...would Earth's year remain the standard for that kind of use?
It's these little details that make a world come to life.