No. They don't. Saturday is always the seventh day of the week. There is no shifting whatsoever. We never skip, shift, or add days to the week. This is what it sounds like you're saying.There are sites which explain the Israelite lunar calendar, but to illustrate the matter considering the following.
The measure of days are equidistant (24hours) and seven days comprise a week. Three hundred and sixty five days is not evenly divisible by seven days. So both in the Israelite lunar calendar and in our current solar calendar the day shifts every year.
Granted, but that doesn't change what day the Sabbath falls. Again, you're not proving much of anything.For example, using January first on our current solar calendar each year that date, like all other dates on the calendar, occurs on a different day from year to year.
Sure, but at no time do we ever shift a day of the week. We never skip a day (e.g. Monday, Tuesday, Thursday...etc.)It cycles through the days of the week.
So what? This doesn't change what day the weekly Sabbath falls on.In a similar manner, there are left over days at the end of each year in the Israelite calendar.
This doesn't change the fact that the weekly Sabbath always falls on the seventh day of the week. More importantly, there is no shifting of the days of the week. What you're pointing out is that the dates change, not the days of the week.So regardless of when a person reckons the sabbath to be made for man our Saturday, our seventh day, is going to shift from and to that fixed day on which it is reckoned as it annually cycles through the days of the week.