Hi Mike
Here's the simple answer to your very good question....
Breaking down the T206 set into 16 sub-sets would have been too complex at that time when Jefferson Burdick catalogued these T-cards. And, actually it still is.
Personally, I would have preferred this if he had each T-brand a set in their own. In recent years, I have put together T206 sets according to the various brands...…
AMERICAN BEAUTY 460
PIEDMONT
SOVEREIGN
SWEET CAPORAL, Factory #30
TED Z
T206 Reference
.