So ... there's pattern on how they locate the entrance rings?
No pattern that I can figure out other than green Hill is the default world for them.
When an event starts that introduces a new world, it's usdually at the main spawn area of Green Hill where it will most likely be the first thing players see.
But when that event expires, the event itself continues allowing other players to catch up to it, but it's relocated elsewhere in Green Hill.
For example "Find Froggy" Event has been relocated not far from the spawn entrance near the shoreline past the spring and bridge.
"Rouge Heist" cave is relocated and fitted into the cliff at the back of Green Hill.
"Jet's Bet" and "Metal City Race" can be found not far from Lost Valley's obby entrance.
I know these are vague directions, I can't find a map on Green Hills to point them out on.
Point is, the only event the other worlds have is "Freestyle Riders" event where Knuckles seems present in all worlds. I'm just saying if there will be more additional worlds in the future, wouldn't Green Hill be cluttered with Entrance Rings eventually?
Plus, if there will be a Halloween and Christmas Event, will they be given new worlds? Will those be world for keeps? Who knows.
