I could not find any images of uncut sheets, but did find another collector's analysis of the sheet layout for this set (unless this is actually your site
). He was also skeptical about the number of SPs designated in this set.
https://www.footballcardgallery.com/..._All-American/
I casually collected this set years ago but never really questioned the checklist or SPs, but your analysis makes sense. Maybe another case in the hobby where something gets noted many years ago, sometimes in error, but it just sticks and people take it as gospel.