The school has several things going for it:
1. Stick time. Even if we only estimate 4 hrs/day of actual flying, with 3 guys, at 10 min flights, that's 40 flights per student over the 5 days. As an instructor at my club, we have a 1-day-a-week flight school, in the evenings. I'm lucky to get 3-4 flights per a particular student per session. So that in itself would be 10-13 weeks. Factor in weather cancellations, other commitments, etc. and one gets to needing the entire flying season...(here in the frozen north). We try to boost the times by also training during other mutually agreed on non-"official" meetups, but that tends to be hard to work out.
2. Degradation of skills with the delays. So much of it is eye-hand coordination. And that just takes repetition to build the neural pathways. Sure, one can over-practice. But also only doing it a little bit, with great separation between sessions, and it all takes even longer. Ask any musician trying to master a new piece....Using a sim can help a lot to combat this. But it still is not optimal.
3. The same points go for instructors - lord knows I can be deficient on achieving the balance between letting the student learn vs flying for him. One moment of "I think he's good enough to catch his mistake" judged wrong...and I repair the plane. Much more time on the instructor sticks for me too would make me a better instructor.
4. A granular level of course instruction. We have a pretty good syllabus we use, and a good outline of what each instructor should be doing during different stages of instruction. But the school apparently has taken a lot of time to greatly define and refine it. We'd never get our instructors to all agree on students only using a particular way to hold the TX.....for example.
5. Focus on a specific student. Having to jump between several students, at widely varying levels, sometimes separated by longer breaks in the relationship ("What were we working on two weeks ago?") also can reset the learning curve to some degree. Concentrating on just one, from first flight to solo, is just so much more efficient....

I've had rare students solo after just 2 weekly sessions. I've got others that took over 2 years (!). One, who took years finally did succeed, and remained so enthusiastic about the hobby, he became an AMA AVP(!). But most humans just don't have the dedication that he had....
Luckily, my average has been between 6 and 12 weekly sessions.

Cost, time to commit, etc. all come into play on whether or not to sign up with the school. Learning to fly can be done either way. But they've been around long enough to show that their methodology does work very well.
I played with the idea of also going "commercial" myself. But then that would turn my fun hobby into a serious job....

What if a person lives in an area with no AMA club ?

Don't mistake my less abrasive tone for acceptance. Yes, I can officially concur Dave's a nice guy. Yes, I can officially concur that Dave's school is legit. Yes, I an aware of just how good Dave is at what he does.

Regardless, I don't believe in what he's doing. And while I understand your defense of his business, it's quite a generalization to assume that you can't get just as good of training at a club. Are there bad instructors out there? Yes. But that's how everything is. It doesn't mean that just because Dave has this big expensive school that no other instructor out there is just as good.

Fact is, I had VERY good instruction. So no matter how good Dave might be, I would never recommend his school to anyone. I just don't believe in it. What he's doing goes against everything this hobby stands for.

I know I would never pay $650 for 5 days of instruction. I've never even spent that much on a single plane. It's not a reasonable price. The only reasonable price is $0. And I won't budge on that.

Now why oh why would someone want to live in such a desolate place ?

If your a Surfer , ya ain't catching many waves in Kansas , you move to the coast ... I guess it depends on just HOW committed you are to your passion .......

Or, like me, build your own field. I got the bug a while after I decided to live where I do.

I guess we'll have to agree to disagree on philosophical terms then. I see nothing wrong with a professional teacher charging for his time. I'll probably instruct for my club next year and was taught by club instructors. It's a service they provide to the club with varying amounts of competence and success. And there is something pure in teaching for the sheer kindness of it. I also see value in an intensive program that a volunteer teacher simply can't provide. One learns much faster at the flight school and isn't going to pick up bad habits. That can be worth the price of an airplane by itself.

In over 40 years of being a club member in at least a dozen clubs during that time frame I have yet to see a club that has a strong instruction program. Not saying that there isn't a club out there that does but I have yet to see that. What I would hope to see is a few hours of ground instruction that includes principles of flight and how to make adjustments on your airplane, radio programming, how to properly care for your equipment etc. then when the flying starts, its a goal based system. First goal is to be able to fly from one end of the field to the other under complete control, next goal fly a right hand pattern, next goal left hand pattern etc. the students card gets signed off by the instructor after each goal. The actual flying should be backed up with club provided simulator time. After a successful solo the student has the option to " advanced " training that includes advanced sirplane setup and some aerobatics training.

All club training that I have seen has been unorganized with each instructor doing his own thing. The school makes great sense to me simply due to the higher organizational level.

That's the difference between a professional teacher and an amateur. Don't get me wrong- I appreciate the guys who volunteer because without them the hobby wouldn't sustain itself. But most club instructors don't know how to put together a logical course of study and implement it like you described.

The club I teach at aspires to that level. There's a mandatory ground school required first, a written manual included with the ground school, a syllabus for the planned flight instruction, a checklist for the instructor to sign off on for each stage of instruction. It is not as comprehensive as speedracerntrixie notes, but does a pretty reasonable job of keeping everyone on track and to set the beginners on course to achieving solo flight. Does have one Instructor designated to be the only one for ground school (consistency), and even has a dedicated instructor that hauls a laptop out to the field on training nights, to go over the basics of how to use a simulator for most effective learning. Those of us on the buddy boxes have periodic pilots meetings to coordinate how we teach, and to swap ideas on what methods seem to work best with each individual student that we currently have on the roster. Anoka Country RC, Anoka, Minn. (Twin Cities Metro Area).

I'll bet your method is pretty effective too. I appreciate that kind of effort. We had a similar system when our lead instructor was a former USAF flight instructor. Now it's just go up and do what you want.