How common and fast is aetheryte teleporting?

[Iscah]

It's implied that being able to use aetherytes at all isn't a very common thing as it was mentioned that only a small unit of Doman soldiers was able to offer immediate support against the Imperial counterstrike at the Ghimlyt Dark, the rest needing to take the traditional route.

Assuming characters are bound by the same teleportation rules as players, that issue wouldn't have been due to a general inability to teleport, but the specific restriction that you need to have attuned to your destination aetheryte. So only the small number of soldiers who had previously traveled to Eorzea would be able to teleport back there.

There might also be additional "realistic" rules about aetherial strength/skill that could prevent some from traveling such a long distance, even if they can travel locally.