Dive sites are going to be determined by current, conditions and generally the consensus of the group. The group size on the morning dives are generally larger than the afternoon. Most afternoons there was mostly just us or a couple of people and dictating a muck dive would be definitely easier. All of the nudibranchs in my trip report were taken from reef dives- so if into Nudi's, you will want to do some reefs. The muck diving was definitely all about the very tiny and microscopic finds. If you are all about muck diving, you may want to consider Anilao instead of Puerto Galera. So, boats do not necessarily have a "pre-determined" site they are going to do- but each of the dives, particularly the morning ones, are typically a collaborative choice between divers, DM's with the currents and conditions taken into count. Obviously, the time of year and number of divers is going to make a difference. Regardless of how busy the resort and time of year, they do not pack the boats full of people. We were typically a max of 6-7 divers in the morning and 1-4 in the afternoons.