Each student having the same problem is not unfair, what you need to look at is how each student DEALS with the problem.
The primary aim of any ATC is SAFETY, that comes above everything else. If what a student is doing is not unsafe, but perhaps inexpeditious or not how the instructor would deal with the problem, is it fair to mark them down on an assessment?
I don't think so, there are as many ways to do ATC as there are controllers, each one develops their own personal style of controlling.
What students need to appreciate are the belt and braces basics, the procedures, standard RT etc..
Once they are at a unit and valid then they will develop in their own way.
Every student should have an equal chance to succeed, as you said, we all learn in different ways, but at the end of the day, if the student can't do the basics or are in any way UNSAFE then they will never make the grade and succeed as a controller.
ATC teaching institutions should concentrate on teaching the basics, the rules and the fact that above everything SAFETY coes first.
Teach the studets these basic skills and the theory required to pass the exams, kick them out into the real world and let them get on with it....