MHK once bubbled...
While I'm sure many will defend the "fast-track" courses, the one thing you may want to consider is that many that defend the course are usually the ones making the money off of the class. Now that being said, consider the following examples:
If you wanted to learn how to golf [ and actually hit the ball straight down the fairway] would you go to the "fast-track" golf-pro or would you go to the one that would spend more time with you???
If you wanted to become a black-belt in karate would you go to the karate school that told you that you could become a black-belt in 2 weeks or would you go the the school that made you earn the black-belt???
If there was a skiing equivalent of "c-cards" would you go to the ski school that "certified" you to go down the double black diamond moutain before you were skilled enough to do so???
The point being is that I could go on all day with analogies and it's often times striking to me that so many people are willing to "fast-track" training in a sport where you are putting your life in an environment that the only thing that will save it, is training..
Remember, you get what you pay for and to me the idea that everything that course has to teach you academically can be taught absent the need for the instructor should set off a light bulb in your head saying that either the materials are too inefficient or perhaps the test isn't inclusive of all I need to know..
Just my thoughts as an instructor that refuses to teach the "fast-track" classes..
Later
I am confident that you are NOT saying that after an open-water / fundamentals course, a diver is or should be at an equivalent of a black-diamond skier, a black-belt, or scratch golfer.
I do believe that learning the academics is best done at ones' own pace. There is little more than high-school physics involved and the materials are pretty good. Instructors can then focus on the areas where the student needs clarification and/or increased emphasis is warranted. "Fast-tracking" through the simple stuff seems to make sense and I know of no situations where someone can just walk in and take the final and be considered to have completed the academic portion.
The issue of time comes into in-water practice. Obviously the more times a person does the skill, the more it becomes a conditioned reflex. Can one get enough repetition and practice of important skills such that they will perform them "sufficiently" in a "fast track" class? I would say no. But then again, I doubt they would in a 3-4 week long class that only meets a few hours each of those weeks -- which was the essence of the question.
So regardless of how quickly one got certified, I think you will agree that the real key [like most things] is continuing practice and drilling the proper technique. And yes, there are things that can be done (like consistent simplified equipment configuration) that aid in this repetition.
The real measure would seem to be after some period of time (diving or not), is there a difference in retention based upon how many weeks it took to get certified. My guess is NO -- unless practiced regularly, most people have completely forgotton.
Perhaps I am making a case for certification renewal and/or more stringent certification requirements.
Otter