That is what happens to many people at the moment I think: they've gotten used to jumping into meta event chains halfway through the meta, but due to so many people wanting to participate, there is a high chance of new maps being spawned rather than people being sorted into existing maps, and since the chain already started it won't happen on the newly created maps. One of the restrictions of a newly created map is that events and event chains on a schedule, that were scheduled to start before the map was created, won't happen on that map. Whether the map persists or closes down depends entirely on the population on that map and nothing else.
There can be one, five or fiftyfive instances of the same map at any given time, but each of those is a full map by itself.
With the introduction of the mega server system, maps are created and closed down dynamically as players join and leave them. Overflows used to be a thing before megaserver, since the game ran one copy of each map per server, and only created aditional, temporary maps if one (or several) server(s) had too many people in a map at the same time, so they overflowed into the temporary map. Technically there are no longer overflow maps in this game, and haven't been since the introduction of the mega server.
