this is an excellent topic. We have some mixed apples and oranges thing going on - and a lot of questions that relate to the Whitlock company issues and their classification - especially how it relates to the issue classified as "T8".
I don't have a lot of time now. The ATC store card with the smoker listing 5 subjects on it is one of at least 3 different examples (CRS - think was fourth with pebbling on the smaller card) of the same image I've owned or seen - size and style you showed, size mentioned in Forbes and classified as T8 with pebbled surface with advertising, and the same size WITHOUT advertising. Why anyone would classify any of the three samples as a "T" card is well beyond me - they are store cards, advertising posters, point of sale trade cards/store cards but NOT an insert related issue. I've had the complete set large (sold) but have a couple of examples in the closet. Uncle Sam obviously the most sought.
As for the other "store cards" (with or without grommet I classify them the same way) - they're neat. I just got the scanner working so I did a small Lillian Russell. Interesting to try and put them in a time line. I assume anything with ATC would come later than those without - it seems Whitlock issued the 4 panel "set" BEFORE the merger (circa 1900 nearly 10 years after formation ATC). There is a MIX of what are stock images and those that appear to be made specifically for them......
(edited to correct minor error)