I once had an AOW student ask to do the fish ID dive in our dive site in Colorado. I told him that if we did, he would be very good at identifying crawdads. but not much else.
In contrast, I did my AOW dives in Cozumel, and it was very valuable. We talked about the variety of fish we were likely to see there before the dive. We talked about habitat and behavior. During the dive, we identified a variety of fish and other life (like worms). I learned a lot.
There is an important psychological phenomenon involved here. When I was in college, I learned that there was once a theory that a certain native American group could not see the color orange. Research dispelled that theory. They found that there was nothing naturally orange in their environment, so their language had no name for it. Consequently, when they saw orange on a test item, they did not have a word for it. This strongly affected their ability to remember it. They could see it, but they could not remember seeing it.
When you are diving and surrounded by fish, being able to name the fish you see has a tremendous impact on your ability to enjoy and to remember a dive. Once you get past that, you can start paying attention to details of behavior. When you are done with a dive and someone asks what you saw, there is a big difference between saying "fish" and saying "I saw some damsel fish guarding their algae patches. I saw a grouper being cleaned by cleaner wrasse. There were a number of sergeant majors guarding their purple egg patches. I saw a trunk fish following a large midnight parrotfish. After the parrotfish took a chunk of the reef, the trunkfish went into the debris and picked out the leftover morsels."