Posted By:
Ed HansTed,
Your hypothesis is a good starting point, but it fails to account for the vast disparity in difficulty among the cards. For instance, in your hypothetical "last series", the toughest card (presumably Mitchell) would be many multiples more difficult than the 30th toughest card (Overall?, Fromme?). The distribution of E90-1 must be far more complicated than this. I suspect that there were at least 5 separate printings spanning late 1908/early 1909 through at least mid 1910. I have been giving this a good deal of thought lately, and I hope to propose my own theory at some point.