I had wondered a bit about the workweek here in Egypt soon after landing. During the very first week of our stay here, I noticed that the HSBC bank was open from Sundays to Thursdays. I came to conclude that just Egypt chose the other two days, Fridays and Saturdays, as the weekend.
I had reason to be in doubt. (I always have an valid excuse for confusion.) From 1981 to 1996, my experiences in the Gulf were that schools operated from Saturdays to Wednesdays. For those who didn't have to put in a half day on Thursdays, that day and Fridays comprised the weekend.
So, it was a bit of a shock to find out that during the last decade, nearly all Arab States had changed to what we've been experiencing in Egypt. In this way Fridays can still be the day for prayers, but the free Saturday means more of the ordinary working week matches up to other locations.