Actually, I've dove with Dressel extensively. I've dove there three separate years with at least 60 dives. I rarely had this happen (dive 45 minutes and have to come up) until I dove there this past April. And then it was only with some of the freelancers. This information is NOT always true. It depends on how busy they are AND what DM you get. The full time DMs usually let you dive your tank, or at least most of it. The contracted DMs are almost always the ones who make you dive 45 minutes and you are up.
I've actually had a number of dives there where it was just the DM and me. I've had quite a number of dives where it was 4 of us. Usually the afternoon dives are less crowded, and tend to have 4 divers or so. However, that being said, I went there and dove 3 dives November 11th, and it was very busy, including the afternoon dives.
The BIG problem there now is that the hurricane destroyed the dock and so they can only board one dive boat at a time instead of two. This REALLY SLOWS THE DIVES DOWN. Normally you get an hour to an hour and a half break minimum between the morining and afternoon dives. I was scheduled for a 9: 30 dive, and i ended up with 30 minutes between my 2nd morning dive and my first afternoon dive. I wasn't staying there, so I didn't have time for lunch.
And I don't know how well Iberostar will handle other dive boats using their pier with how busy they are. The day I was there, I think 8 boats went out in the morning, and at least six in the afternoon. I wouldn't be surprised if there was a pier fee with the dock beign broken. The marine park is holding up Iberostar's repair of the pier.