A recent news item on international communication as it is today:

AT&T faces the many hurdles that all companies have in its endemic corruption and bureaucratic inefficiency.  Iran  works on a calendar different from the West's, with different months and a Thrusday-Friday weekend.  There is the possibility of opposition from conservative clerics and Iran's supreme leader, Ayatollah Ali Khamenei, who could end the arrangement in a flash if he felt it was inappropriate.

When West only considers its work week and calendar, it forgets that half of the world neither operates on the same calendar or work and they have their holy days just as majority of the Christian world in the West.

This should caution the certainty that a day given only to the Israelites, a very small group of people in Palestine should influence the entire world to observe its holy days and festivals, given only for them and applicable on one time zone--something totally unimaginable some 4000+ years ago.