Learning things out of order will always occur unless you put all your starting students in a specific course where they need to do each step individually before being allowed to pass on to the next. As such not being able to see or hear what other students on next steps are doing.
This was ways of old, not way of the europeans in a modern society. So every time a student miss a few classes which they will for sickness, vacation, working overtime, training something else... you name it. They will miss out on parts of the teaching and continue where everyone else are at the point when they return. Perhaps not a good thing but it is reality, and another thing that is reality as well. In time those students have a chance to become just as good and sometimes even a lot better than other students.
Their path is not doomed from the start.
I disagree with this teaching method and class management.
I was the one saying I cant do what I am supposed to do in that drill properly if the height difference is too big.
What's causing the problem is not height difference, but what you have been told you're supposed to do in the drill.
You are the one saying this drill should just be about the technique of using your elbow properly. No realistic force management, no reaction to force. No reflexes, no sensing nothing. So you are the one describing the drill as purely technique based.
A martial art technique in English usually means something like a kick, punch, block, lock, throw, etc. as it is applied. VT isn't based on this technique vs that technique. That's why we say we are not a technique-based system, but a principle-based one.
Contraction, expansion, and rotation of the elbow are not techniques against other techniques. They are just basic elbow mechanics.
Doing some specific action to control your opponent's arm, like you said you do, is a "this vs that" technique-based exercise.
Chasing hands are what you are doing given that you do the drill in a forced way to focus on elbow without any care for what your partner is moving, the angles, any potential force (Or you claim there is no force ever? Nice going then to have your students so in control they have no force in their move.)
DCS is not a fight. I'm not looking at my partner as an opponent whose arm I must control. I'm not even thinking about hitting someone. We are simply using each other's arms to mutually train our elbow control together in an abstract manner.
You are thinking stick, feel, roll, control, hit, this technique vs that technique. It's a technique-based approach and you have already discovered for yourself that it doesn't work and you need to change it.
Here is a little newsflash for you, you are not me. You have no clue what I do, or how I do it.
You just explained to me what you do and how you do it. And you are not the first WT guy to have done that. I've had this conversation in person.