It sounds similiar to the no limits fallacy in it's long term application, (In my opinion), but I'm not sure how to classify the base opinion itself (No differentiation between weeks, etc' other than the dates without a special 7th day)."If there was nothing special about Saturday/Sabbath then there would be nothing to differentiate between each week, or month or even year"
Sabbath is Saturday, the 7th day of the week, and is "Holy" (Same as Sunday for christians).
(And no, the argument over what should be done on Sabbath by Jews/Israelis, etc' isn't relevent to it [Though I defined it as Mental but not physical rest]