The Monday through Sunday workweek usually lasts eight working days, and the Monday through Saturday playweek usually lasts four working days. When you add in the possibility of public holidays, that overall amount increases to 10 working days, and twelve-playing days.
The days themselves are simply one element of the calendar, and there are plenty of others. Any seasonal modification is shown in the calendar, and it tells us when and where to go throughout certain times of the year.
Image source: calendarpedia.co.uk