You definitely want to see the student in the water before dong the deep dive, whether it is a requirement or not. I have one very memorable incident to show it.
I had two AOW students, and we did 3 dives the first day together, including navigation. On those dives, one of them was really bad on air usage. I worked hard with him on that, but he was still pretty bad. The next day we led off with the deep dive, and I had the two of them plan a multi-level plan with turn pressures based on what we had learned about the SAC rates the first day. Well, when we went deep (about 95 feet), his SAC rate went from bad to horrendous--we were at the first ascent pressure the second we reached that depth. Because of that first day, his buddy was right on top of it, and I watched with satisfaction as that buddy monitored his gas and led us all to the surface with the proper safety stop, etc. The air hog finished the dive with 400 PSI, and I used less than 800 PSI--and I was not remotely trying to conserve air. I am very glad we were watching for that because of our previous dives. I would have hated to have that incredibly bad SAC rate be a complete surprise.
I had two AOW students, and we did 3 dives the first day together, including navigation. On those dives, one of them was really bad on air usage. I worked hard with him on that, but he was still pretty bad. The next day we led off with the deep dive, and I had the two of them plan a multi-level plan with turn pressures based on what we had learned about the SAC rates the first day. Well, when we went deep (about 95 feet), his SAC rate went from bad to horrendous--we were at the first ascent pressure the second we reached that depth. Because of that first day, his buddy was right on top of it, and I watched with satisfaction as that buddy monitored his gas and led us all to the surface with the proper safety stop, etc. The air hog finished the dive with 400 PSI, and I used less than 800 PSI--and I was not remotely trying to conserve air. I am very glad we were watching for that because of our previous dives. I would have hated to have that incredibly bad SAC rate be a complete surprise.