The Monday through Sunday workweek usually lasts 8 working days, and the Monday through Saturday playweek usually lasts four working days. When you add in the possibility of public holidays, that overall quantity increases to ten working days, and twelve-playing days.
The days themselves are just one aspect of the calendar, and there are plenty of others. The months of the calendar represent various seasons, and the time between each of those months offers us the seasonal cycle. At the start of spring, the temperature level is high and the days are warm, while at the end of winter season the air is cold and the days are cold. Every season has its own special time connected with it, and the calendar helps us keep an eye on all of those shifts. Any seasonal modification is reflected in the calendar, and it informs us when and where to go throughout certain times of the year.
Image source: calendarpedia.co.uk