Change instructors now. It does not matter if he is used to flying fast or slow. If he cannot tailor his lesson plan to the students needs then he is not an instructor.

This is even worse should your trainer be typically overpowered which is so common these days. That makes teaching the use of the throttle even more important.

The fact that he is adamant about speed just points out his inexperiance in teaching and he is fearfull of you stalling and his inability to handle the situation.

Blasting around at full throttle with their trainers is a hugh problem these days that you will see many students as well as many instructors doing. It certainly does nothing for the student in helping him to learn how to "Fly on the Wing".

Bottom line it is not "the proper way" and should never be "the usual way".

John