My impression is that the 1956 cards were oversized and that the slits had 110 cards (10 x 11) each. there is one complete series 1 slit which bears this out.
I have seen a slit for the 3rd series and the 4th series. Both series were 80 unique cards, with 110 card slits, and had a pattern of 10 rows by 11 columns (in a horizontal layout). Columns 2, 3, 4 were repeated at the right side
56 Topps 4th Series Sheet Front.jpg
56 Topps 3rd Series Sheet Front.jpg
1956_sheet_series_1_full.jpg