Three kind of calendars were used in Two Clusters.
Those who lived in “inner Sol”, meaning Venus, Earth, Moon, and Mars had a strong tendency to use the calendar that is widely used for our time where there are distinct seasons.
However, those who lived outside of inner Sol and those who stayed in space mostly used what was called “universal calendar”.
A universal calendar was developed to replace the traditional calendar since concept of spring, summer, fall, and winter was long lost.
The universal calendar had the same 365 days, but concept of month is removed. The day would be read in 1 to 365. For an example, Year 9599-200 would mean 200th day of year 9599.
This was de facto way of date recording for logs.
Another form of calendar was “seasonal calendar” which is often used by civilians in Andromeda cluster as well as Outer Sol (Jupiter and beyond). There were four seasons, consisted of 91 days per a season, in the seasonal calendar. The last season has one more day to make it 365 days.
91 + 91 + 91 + 92 = 364
A usage would be like this: "My birth day is season 3, 87th day." & "That place is opening on season 1, 13th day."
On all official documents, universal calendar was used.
Because of different standards of calendar, it was important for employees to keep track of their wage payment period. Some companies would pay wages monthly (30 days) while most government facilities paid wages seasonally (91 days). In general, seasonal pay was the most common.
The concept of holidays was often lost due to the fact that those who worked in space did not really have the luxury of taking days off without dire consequences.
Furthermore, powerful clans had their own holidays and ordered their clan members not to follow national holidays.
Thus, in Two Clusters, national holidays did not exist. The only universally accepted day-off was Sunday of a week, for civilians at least.
While there was no official national holiday, there were festivals and specials days. But these were different on each planet.
For good examples, “Burning festival” would be held on Mars whenever there was clear sky. Clear sky on Mar was a very rare occurrence. Therefore, whenever there was clear sky on Mars, Marians would prepare for the burning festival in evening.
For Venus, there was the New Year day on the 1st day of 1st season each year. It was considered a Venusian holiday which the O’ren and the Vues complied.
On Earth, the Bau’s holidays overruled everything. Due to the long history of the Bau, there were actually too many special days.