The industrial school model is that of even progress. There is the first grade. Then there is the second. Then the third. Students are expected to build their knowledge in parallel across a variety of topics in a linear and additive way.
The reality could not be more different. Learning abilities and useable knowledge bases are wildly different from student to student, and month to month.
Imagine you are on a scooter, and your assignment is to move ahead ten feet. You would do this easily, and might get praise for doing it so well.
Now imagine you are in the same class, but you are in a helicopter for the first time. You are told to move forward.
You press a random lever and your rotors spin loudly. You go up and then crashing down. The other students on their scooters look at you angrily - you are causing a scene. The instructor tells you to move forward again, but reduces the goal to only five feet, noting your difficulty. You press something else and lurch backwards. Now the instructor is furious. Meanwhile, a red light is flashing in your cockpit.
The final rub in this analogy, of course, is that a helicopter is a much more powerful and valuable vehicle. Ten years later, you are going to want the helicopter saving you where scooters could not.
We are so much more diverse from person to person, and even month to month, than we have internalized. And our tools keep changing on us - scooter one month, helicopter the next, even a cinder block the month after that. Some things are effortless, others are impossible.
Any structure that does not embrace the chaotic diversity of talents and the temporary whims of abilities is doomed to a lower common denominator approach, ultimately along the way creating a corrupt moral framework around temporary abilities measured by incomplete short-term standards.