Thank you TF! Sounds dicey trying to get moorings. What is the latest time of day that you have a decent chance of getting one?
I don't think that there is any single answer to that question. It varies so much at different times of the year, and different days of the week, and different weather conditions. While I mentioned a couple of times that mooring balls were in short supply, they were always when weather conditions would cause more boats to seek protection (some of which might leave as soon as the weather cleared). Boats seemed to come and go during all times of the day. Remember that most of the balls are free for day use, and I don't think that they come around to collect until late afternoon. So there's always a good chance that someone would depart late in the day before they have to pay. Bottom line, it does not matter how many balls there are, as long as it's greater than zero.
We were glad that we weren't there between Christmas and New Years, as I suspect there is so much traffic then that mooring balls may often be filled to capacity. But outside that, it's probably a crap shoot with pretty good odds. Maybe someone who lives there can fill you in better.
We were determined not to let fears over mooring ball availability affect our fun. We weren't going to go racing out of the mooring field early in the morning just to get to our next destination. We were going to sleep in, eat, snorkel, and do whatever we wanted to, and leave when we were ready to. We figured the worst that would happen is that we would have to anchor (which we preferred not to do because we're not familiar with the quality of hold in this area) or we would have to pay a little more for a slip in a marina.
Don't forget that overnight mooring ball rental is a business, and if there's sustained demand for them, then there's an economic incentive to put more in. This might make the anchoring folks unhappy as they see their free anchoring areas encroached, but it's good for the environment since it protects the coral better than people dropping anchor all over the place.