Flash picture with eyes open? Divide by 3

I think this rule applies to flash photography, but the idea is universally applicable. Flash is not long for this world ... fortunately.

Rule of thumb to avoid photographing people with their eyes... (kottke.org)

... to avoid photographing people with their eyes closed: divide the number of people by three (or by two if the light is bad). ... Jeff writes: 'Way back when we only used film I learned you could tell before looking at the photo whether someone blinked by asking them what color was the flash. If it was white or bluish white, then their eyes were open. If it was orange, then their eyes were closed and they had 'seen' the flash through their eyelids.'