You are quite right. I hate it when I want to order something next day and then realize that tomorrow is an "off" day. The more contiguous off days, the less advantage there is for expedited shipping. That is, the ratio of time spent en route to time spent in off days decreases to the point where next day delivery would become comparable to 5-day ground shipping. It still gets there four days quicker, but as the limit of off days approaches infinity, the four day advantage becomes increasingly negligible. It would be like waiting a year for a "next day" package to arrive, and saying, "oh, I only had to wait 365 days rather than 369 days". So you can begin to see that with more off days, you are effectively devaluing next day shipping. A crime against humanity, to be sure.
In short, I agree with your statement, and the guy above you is wrong, just plain wrong. If we are going to have another off day, it is far better to have it on such a day that the off days are as evenly spread out as possible. Consistency is usually best.