gamerprinter
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We have 3 GMs at our table, sometimes we rotate the GMs chair while in the same setting, though more often each will run a short campaign where each is the only GM for that game. All 3 GMs create our own settings, I don't think I've played in anything, but Greyhawk, in the earliest days, and even back in 1e we were developing our own settings then. We did run Dark Sun back in 2e (I was a player, and for whatever reason, I hate Dark Sun), because a 4th GM, who has since passed away loved psionics and loved Dark Sun. Now we might have borrowed aspects of Menzobarrenzan boxed set in one of our Underdark games, but even then we didn't use that city as is. I've never been a fan of the kitchen sink.
Consider that I've even published a homebrew for Pathfinder through Rite Publishing with the Kaidan setting of Japanese horror (PFRPG) which is an extremely specific setting, not just feudal Japan, but as the first of its kind with Japanese horror as its theme. Kaidan, although designed for PF is very gritty, but more esoteric than down to earth.
Consider that I've even published a homebrew for Pathfinder through Rite Publishing with the Kaidan setting of Japanese horror (PFRPG) which is an extremely specific setting, not just feudal Japan, but as the first of its kind with Japanese horror as its theme. Kaidan, although designed for PF is very gritty, but more esoteric than down to earth.