Agreed, glad you called this out! I was thinking about rambling about this, but this is a topic I can go on and on about, and I was already off to a slow start today...
Please ramble! I've actually though much about this as well. It kind of forces a "holy day" because without one nothing fits into one week with any period other than "every day" or "every week" - be that week 5 or 7 or 11 days. I've heard that the seven day week was independently developed at least three times in ancient times across disparate cultures as well.
