Exactly. This test (although interesting), is next to useless.
We all know (or should know, if we're looking at spending mulitple thousands on new brakes), that braking is mostly a function of tyre grip. Throw 50" brakes and 80 piston calipers on a car, and it'll still lock up the wheels or engage ABS at the exact same point as your stock brake setup. If you can lock up your brakes with your stock calipers, pads and tyres, what improvement is putting MORE braking effort into the system? The tyres are still going to lock up at the same point and stop you braking any harder.
For all intents and purposes (discounting pedal feel, etc), big brakes of any brand or size, will not improve your braking effort noticeably in the one-stop test on street tyres.
What DOES change, is if we alter TWO factors in this equation?
1. What if we increase NUMBER of stops? As you can see in the test, larger brakes are able to dissipate more heat, more efficiently... resulting in more consistent braking, and resistance to brake fade.
2. What if we increase TYRE GRIP? Throw a set of semi-slicks onto the car, and the level of braking you are able to achieve before locking up the brakes is massively increased. This means that you're introducing a MASSIVE amount of extra heat into the brakes, and at a MUCH faster rate than you would ever ever ever see on street tyres. That means that the heat dissipation abilities of your brakes really comes into play now. They need to shed that extra heat much more efficiently, otherwise meet my little friend "brake fade".
Now to REALLY make those big, expensive, shiny, brakes earn their keep, lets combine both of those above factors and do lots of stops on semi slicks. Aha! Now we are accurately testing the difference between stock brakes and big brakes, in an environment that we would be applying them in.