These guys are very pretty, and only come out around dusk for about 20-30 minutes.  I have seen them a few times during the day, but only buried in the coral.  Every day, they come out to mate.  Since they are a popular thing to see, and are in a small area, seeing them often ends up being a scrum.  Imagine 15+ divers arranged in a circle around a circle of broken coral about 3 feet/1 m across.  Add a little bit of surge, and "scrum" is too nice a word for it....  I'm happy to have seen them, but not my best dive experience ever.