My thought on the matter is pretty simple: it should accomplish whatever is necessary for the plot, and is agreed upon by the players involved. It shouldn't be used generally or unnecessarily because its one of those things that stretches plausibility and continuity.
With regards to Au Ra... I suspect it shouldn't be looked upon as a "single day" event, rather although they'll all unveil themselves at once its more reasonable to understand it as something that has happened over a little bit of time. Once the first Au Ra showed themselves and people began to acclimate the rest rather quickly took off their disguises.
With regards to Au Ra... I suspect it shouldn't be looked upon as a "single day" event, rather although they'll all unveil themselves at once its more reasonable to understand it as something that has happened over a little bit of time. Once the first Au Ra showed themselves and people began to acclimate the rest rather quickly took off their disguises.