Identifying 1936 vs 1937 EXHIBIT 4-on-1 from one another ??

[Spartan]

HOW does SGC, PSA or anyone TRULY, ACCURATELY determine a 1936 EXHIBIT 4-on-1 card from a 1937 EXHIBIT 4-on-1 card, esp, when the 4 players and photos are ‘identical’ within the two years of issue… Example, the card with FOXX, GROVE, CRONIN, FERREL. One particular reference on the internet tries to define some reason in the text, but I do not find this to be the case when looking at 1936 and 1937 graded exhibits 4-on-1 that I own or can view on eBAY.... the rule below either is not true, or not followed by the grading companies...

1935 16 slate blue 4 on 1. Single color only.
1936 16 olive green 4 on 1. 'Ptd. IN U.S.A.'
1937 16 green, blue 4 on 1. 'Ptd. In USA'
1938 16 brown on 1. 'Made IN USA'

Of all the 1936 and 1937 exhibit 4-on-1 that I see like on Ebay labeled in SGC holders, they all seem to be “Ptd. IN U. S. A.” , no differences, so how the decision to define it as 1936 or 1937 issue I do not know. The accuracy in the registry on these two issues could be quite confused. Does anyone concur or can you give me a way to be certain the identification is extremely accurate and not arbitrary guesswork ? I don't know if this SGC graded card is truly 1937 or 1936. Thanks everyone for your considerate and knowledgeable feedback.