I was doing up a calendar for my campaign, to keep track of time Gygax-style, and I set up weeks exactly the same as we have: seven days, divided into five official working days, a day off and a holy day. It was simply a convenience.
But when I was working out how long it would take the PCs’ hirelings to move 80,000 coins out of the bottom of a dungeon (14 12-hour days, in case you were wondering), I wondered whether or not the hirelings would insist on having Templedays off.
It probably didn’t make that much of a difference (just two more days, and maybe an extra 30gp), but I think it’s important for the verisimilitude of the world. Now I want to make a whole list of actual public holidays. What sorts of verisimilitude-y things do other people do?