ButHowever, when he studies with a group he has to continue step by step with his groupies.
AndTherefore, by this maybe he has to put more time for parts he completely know, or even worse he can't eliminate his difficulties during a group study because of not putting enough time for that part
As I know that, we do not use 'but', 'and' at the begining of a sentence.
scientific level
how about the replacement by intellectual capacity
studying will change toturn into tutoring
For student with higher scientific level of course, studying in a group is nothing but waste of time.
These are all my comments about your essay. By the way, you develop and express your ideas in an excellent way, so that everyone can fully understand your meaning.