Actually, in the 1960s, as the arcades closed, ESCO tried to sell its cards in packs.
I thought this might be interesting to add to the discussion to show how flexible the company's printing was:
As you can see, this sheet has Salutations of Pafko, Feller and Elliott (allegedly printed only through 1946), a 1949 Rizzuto (with the An Exhibit Card marking at the lower left), a Robinson, and some basic mid-1950s cards. The Newcombe card, for example is likely from the 1950 or later print run. Newcombe made his big-league debut on May 20, 1949. Unlikely that an early season call-up would be in the 1949 set, and there is no "An Exhibit Card" marking on Newk's card, which would be on a new 1949 card. The Ashburn also is not the AEC marked version. Ashburn's first game was April 20, 1948. He does have an AEC version from 1949, which I think can rightly be called a rookie card:
They also misspelled his name "Ritchie". There is also a clear 1950 card based on the size of the MADE IN USA marking:
Still with his name messed up. This is the one that shows on the uncut sheet. Here is Richie Ashburn with the misspelling corrected:
I think the sheet is likely a 1950, so the Robinson would have 3 years printing at that point.
The rookie stuff may be difficult to solve, but the ESCO card is a career-contemporary card with a nice image.
Dennis, if you want to see some Robinson eye candy, there is a thread on the postwar board that is all Jackie, all the time, and the collectors here have posted some rare and really interesting cards there.