I agree there does not seem to be a standard. You usually have to read the cover plate on the strobe but that may not be practical if you are a visitor.
I agree this might be a good place for a convention. Now days we do seem to have an array of emergencies they want to warn you about, particularly in "secure" locations.
I remember in some places I worked there was always some kind of strobe going off when I was in a room because my clearance wasn't high enough.
