Initially, Coil had a complex and well-thought out calender. But over the years, as the population grew and as more and more people entered the city, unable to read or barely speak common, the calender was replaced with a simple method of numbering the days and the months.
So, Monday February 12 is merely the 12th day of the 2nd month of the 2007th year.
All months are 28 days long and every 7th day is a day of rest.
Seasons are three months long. The year starts with Spring. And the first day of each season is a holiday. Beyond that, people aren't allowed much time off, except for important holiday's like King's Day and Soldier's Day.
The poor have to get back to work, after all.
Of course, the rich take time off whenever they like.