Shared working days across countries
Pick two or more countries and see how many days in a period every one of them is actually at work. Each country loses its own weekends and its own public holidays, and the days that survive in all of them are the ones a distributed team can genuinely rely on.
Why the overlap is smaller than people expect
Two countries with ten public holidays each rarely lose only ten days between them. Unless the holidays coincide, the losses stack: a team spanning both can be down to twenty days where each side individually lost ten. Add a third country and the erosion continues, which is why quarter end planning across regions tends to run short of time that looked available on a single calendar.
Weekends compound the same way. Where one country rests on Friday and Saturday and another on Saturday and Sunday, the shared working week is four days, not five, before a single public holiday is counted.
The table above lists only the asymmetric days, because those are the ones worth planning around. Days when everyone is off need no coordination.