I've been the GM more often than not (and prefer it that way) since 2018, but before that was a round-robin situation in my old group. Nowadays I'm happy to sit behind the screen unless someone in the group gets a wild hair.
I consider myself an only GM because those that try to run games do so for 4-5 sessions and then take a forever break...that's happened twice in 10 years. These days I just decline offers to be a player because too many wannabe DMs (including my players) let me down.