There is quite a history behind this sheet. According to Beckett Auctions, the owner was a former photographer for the companies that made cards for Kellogg's. He did have many other proof sheets in the auction, so I might as well check this one.
The cards are placed in numerical order on this sheet. From opening other Kellogg's factory sets and looking at other uncut sheets, this doesn't seem to be the case. Maybe 1973 was different because there was a different supplier of Kellogg's cards that year. This set is the only one without the 3-D effects.