I've had a tough time finding info on this via your basic google search, so here goes.
As far as I know, there were two basic cartridge designs for the SNES in North America. The first one is a flat, blocky rectangular design, and was used approximately from 1991-1993 or so. A redesigned cart came out sometime in 1993 and had a diagonal groove carved out on the bottom half of the cartridge. This design was used for all games that came out after its introduction. Incidentally, I believe this was about the same time Nintendo stopped including the plastic cart sleeves with the games.
First of all, does anyone know why Nintendo made this minor alteration in the cartridge design? I've wondered about this since I was a kid.
Second, what is the exact time frame of this switch. Is there a certain date or month that can be pinpointed as the day the redesigned carts came into circulation? How many games were released of each cart type?
Third, could there possibly be variants of particular games which were released around the time of the switch which were circulated with both the original cart design as well as the updated design? For instance, perhaps the game was initially released before the switch, and then had a second printing after the switch which used the updated design? I imagine certain Player's Choice games would fall into this category, but what about other games?
I appreciate any insight you guys can provide. Thanks!