You say you had a hard cavern class, cool, so what should the OP expect then, from a hard cavern class? Posting about this would be helpful to let him know what to expect basically... and I too am interested in what constitutes a hard cavern class. Like, how did you find it in comparison to Cave? What things did you struggle with? What tips do you have? And so on...
The beginning of the class that I took was not so "hard" as it was frustrating for me. I usually like to do things right the first time and then move on. I thought I would list of few of the things that caused me top have issues the first day or so.
1) I came down with gear that I assumed I would be using for the class. Its my normal set up for single tank OW with an extra reg set up, lights etc. The first day before we even started with the book work. We disassembled all of my gear and spread it out. We reassembled some of my gear with some of the instructors to get a set up with doubles that would work best with what we had. Now I had a BP/W with two regs, long hose, single SPG, etc. Most of which was different from what I normally use. I would try and use the gear that you be using in the class and get some time in it.
2) Placement of gear... The D rings on the harness were in slightly different locations than on the set up I normally use. Just having the shoulder rings a little higher takes that extra thought and time to find the ring or clip. My light canister moved from a tank mount to my waist belt. Not a big deal, but once again you have to think and find it in its new location. Spare lights went from mid left strap to high on both shoulder d-rings, about the same thing just had to think about where thier clips were.
3) Make sure that you understand what is expected of you before you start the dive. A number of times there was a communication problem that took time to sort out before we could continue. This got way easier as I got to know my instructor better through the course. Something simple like when I was asked for my air pressure. I used a different method than he wanted, so we would stop until I gave it correctly. Once again, just another little thing that I had to think about before it became second nature.
4) When doing drills, like laying out line and doing tie offs, I should have been more confident in what I was doing. I spent time at each tie off for his nod of approval before doing the tie. It would have been better to judge for myself and then have him correct me if I was in error.
5) As far as the actual drills went, I actually had no problems with them. No viz, no mask, air share etc, lost line, lost buddy, valve drills, low overhead, etc were one of the main reasons I took this course. ( other than the fact we were in some really cool caves) I wanted to add a little more complexity in my diving.
If you notice from the first few items I listed, that all of the small things that normally won't be an issue in OW seem to take up too much time and thought process during the first couple days of the class. If I would have had an issue, I would hate to have to use the time for something that should be second nature. It would have made the start of the class much more productive if I would have worked out these things before I started the class.
One last tip. I don't know if its an issue for most veteran cave divers, but by the end of the week, both of my thumb tips were raw from working the bolt snaps. When I got home a took a small file and removed all of the sharp edges from the bolt and slot edges. It seemed to be worse with the high end SS snaps......