Are there places or cultures that don't use the common Monday through Friday week?

This is something that’s relevant to my company, which makes software for private schools. We are updating the lesson plan portion of the software, and the product owners are making the lesson plan always be M-F.

But sales is saying we need to focus on support of international schools. Right hands and left hands, eh?

So, what parts of the world don’t do Monday to Friday for their default work/school week?

This Wikipedia article covers it:

The Middle East is mostly Sunday through Thursday. Saudi used to be Saturday through Wednesday, but recently (a few years ago) they changed to match the rest of the GCC.
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Israel is Sunday - Thursday.

Friday is the holy day for Muslims.
Saturday is the holy days for Jewish observance (Technically, sundown Friday to sundown Saturday - which is more relevant in northern latitudes. B&H in New York can shut down IIRC at 3PM Friday so people can get home before the winter sundown.)
Sunday is the shopping day for Christians.
There’s some Christian church group I think that thinks the real Sunday is Tuesday.

The Seventh Day Adventists observe the Sabbath on Saturdays (sundown-Friday to sundown-Saturday), but aren’t as strict as Orthodox Jews on allowable activities.

Laborers here will work Monday through Friday, and a half day on Saturday.

Sunday is the shopping day for Christians? Not according any of my Christian schooling. Shops aren’t even supposed to open on Sunday (and don’t in many Christian countries). Saturday is shopping day.
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There’s not much of surprise in that article, but when it’s Monday, let’s say, in the U.S., is it necessarily Monday everywhere else? What’s to stop some wacky country from having Thursday when everyone else is having Monday? Or from switching up the order?

The workweek in North Korea is Monday to Saturday.

I presume this isn’t a serious question.

In India, the traditional work week is Monday to Friday and half day Saturday. However, government offices and foreign-based companies are closed for the full day Saturday.

They say sarcasm is lost on some people…
They say a good comedian never explains their jokes, so…
In Canada, and presumably to some extent in the USA - Sunday store closings used to be seriously enforced to support “Christian values” whether the law put it that way or not. The restrictions have been steadily loosened to recognize multicultural values and the separation of state and church, to the point where in many jurisdictions stores are pretty much open much of the day. The only legacy seems to be slightly shorter store hours in some places, and some places still prohibit the sale of alcohol for a more extended time or all day.
Not sure how this applies to other traditionally Christian countries like in Europe.

Also, I haven’t run across whether Hindus, Sikhs, or Buddhists have a particular observance weekday. Also AFAIK while some places may support a different calendar in some respects, almost all also use the Gregorian calendar as an international standard, including same weekdays. (There’s the Jewish calendar, Chinese calendar, Muslims have their own calendar, Japanese count years by Emperor, etc. - and there will be particular days of observance associated with those.) Unless your organization is the size of Microsoft, good luck coordinating all those. Your best bet is to make all these aspects including “school days” of the week a programmable option in configuration settings with a set of defaults.

The French Revolution tried to impose a completely different calendar way back when, but it didn’t stick the way the metric system did.

But to get back to the OP, also remember that private schools with a religious bent may also be inclined to run religious instruction on a separate day - i.e. Sunday school or equivalent. This particularly if they are attached to a church or synagogue.

Indian religions don’t have a tradition of mandatory weekly attendance at a particular place for observance, so, no, there isn’t a day that has to be a weekly holiday to observe religious obligations.

A devout Hindu, for example, has a shrine right in his or her residence, perhaps even next to the bed. Religious duties can be executed as frequently as he or she feels necessary.

I’d be more worried about all the reasons a U.S. school might have a class on Saturday – make-up classes, extra (test-prep or whatever) classes, classes for continuing education/non-traditional students, etc.

Restricting lesson plans to any specific days limits the usability of the software and it’s potential market.

It should allow the school to choose a weekly schedule. Default it to M-F.

In Egypt the work week is Sun-Thur, with Friday and Saturday the weekend.

I was amused to learn that in Dubai (and perhaps elsewhere in the Middle East), the TGI Fridays restaurant chain calls itself TGI Thursdays.