Are the Shards in separate dimension or are they physical locations?

[Iscah]

The way the shards have been spoken about before, they're all overlapping, just on different "planes", as if they're on different "frequencies" in the same "space"...but this may no longer be the working assumption.

You say that like there's a specific reason to reconsider that assumption - is there?

I don't remember there being any suggestion of other possibilities. Is there a reason to question it beyond "we don't know the technicalities of how it works in circumstances the story hasn't explored yet"?

[Anonymoose]

You say that like there's a specific reason to reconsider that assumption - is there?

Not unless you take the Exarch's diorama too literally. Though there was no reason to reconsider the assumption that there was one red-masked overlord per shard, either, and here we are. Now Elidibus was one of the Fourteen, the Source had two unsundered Overlords, there were still 15 Ascians in the 2.3 cutscene (so I guess they replaced Emmerololth pretty quickly, too, huh?) and the math is all wonky. I don't take anything for granted when Square Enix's goal is to tie up loose ends.