Even two morning and two afternoon dives is a lot for Coz. For the most part, Coz diving is boat diving, and it's not like in some places in the world where the sites are just a hundred yards offshore--the rides out and back can be long. This makes for a very long day. Four dives a day for a week would exhaust me and leave me little time for exploring the town (that is, stuffing myself with Mexican food). If I recall, there is at least one dive op that will drop you off at a beach bar for lunch, thereby avoiding the boat trip all the way back to town, which seems to me to be the only practical way to get four dives a day in (excluding night dives, which obviously get you back to town late--some restaurants may already be closed).
With some of the southern sites currently closed, I don't know how the above may be affected. Maybe shorter rides out and back are a silver lining.