IMO, there is no substitute for diving. More individual reading or classroom sessions may produce sharper theoretical divers (or e-divers if we're talking about online reading), but you can't learn to dive without getting in the water, and the more you are in the water the better you will learn to dive.
Just making the same dive, in the same puddle, over and over again does very little to stretch your skills, you need dives that expand your scope.
No argument there at all, with either point you guys make. I could write up the basic instructions for juggling, and anyone with functional comprehension could learn the theoretical steps in just a few minutes.
Knowing the theoretical steps is easy. Keeping three tennis balls moving smoothly and continuously between two hands is another matter altogether. Training the muscles to make consistent tosses left to right and right to left, over and over, can only be accomplished by repetitive practice.
There were some very basic skills I was practicing even before class, and which I plan to keep practicing. We plan to spend a lot more time in the pool at the Y, swimming laps to strengthen the muscles and build more endurance, including spending lap-swimming time practicing staying next to my buddy. I want to learn and develop those skills that are going to keep my wife and I off that statistics list.
I do have to wonder, though, how many new student divers don't share that same kind of involvement in their own training and development? How many go in to scuba training with the same kind of mentality they might go into a training session at work? - "All I need to do is get enough to pass the test, and then I can get back to what I was doing."
No matter how excellent the training program and instructor might be, the unpredictable weak link in the chain is the student. There's always someone who just doesn't pay attention, or doesn't think it applies to them, or whatever, and no matter how much you try to train them, they're not going to apply it. Based on what I've read here, some of you instructors have no problem failing someone like that, and not advancing them to actual open water dives.
I have no doubts that some of those divers in the quoted statistics were ones that should have been told by their instructors, "I'm sorry, but you are simply not ready yet."
When I learned to ride a motorcycle almost 30 years ago, there were no readily available motorcycle rider safety courses in my area. I listened to advice from experienced riders, and then just had to learn how to apply it on my own. One thing a "veteran rider" told me was that if I managed to get through my first year of riding safely, the odds were good that I'd have good instincts and skills to be safe thereafter.
I find it interesting to read a similar concept mentioned here on scuba.