Sorry man but I don't agree. there are just some skills that need to be taught by a qualified instructor that repetition won't teach you. This starts at the OW level and continues throughout your diving days.
For example, I am an SSI Dive Master, I have completed all the training requirments and checkout dives, along with the required amount of logged dives. Now as many times as I've dove at Ginnie Springs I would never condider passing the Reaper sign until I have the proper training required.
Let me ask you this. Your diving a wreck you have never been to before, neither you or your buddy has had any previous dives on or in a wreck enviroment, nor do you have any wreck training, Do you penetrate? Without knowing what to expect, what additional gear is required, ect. ect. I would'nt.
You're planning a nite dive, do you know the proper equipment needed, how to give your buddy the OK signal in the dark?
These are the skills you'll learn in advanced training. I remember you said you were going to take stress & rescue, theres alot of skills to learn in that class, how to reconize stress in your buddy before during and after the dive, how to surface your buddy when he is freakin' out, and so on. These skills my prove invaluable one day.
Remember one thing, if your diving with a buddy, his/her life may one day be in your hands, or visa versa I'd be more comfortable with a buddy that has those C-cards, and is'nt more or less self taught. I dove with quite a few buddies in the past, all fairly good divers, but I only have 3 that I actually enjoy my dive with, one of them being my instructor, I know that if I get into trouble they have the training to handle the situation.
All of this goes along with the the repitition diving, I'm by no means the worlds best diver, I learn something everytime I dive, and I'm certainly not trying to be a smart ass, or promote a LDS, its just my opinion that those C-cards you get do mean something about your skill level.