Upgrade training is very different from Transition training.
It has different goals and requirements from both the instructor and student.
The student has probably been flying his aircraft type for many years and should know his stuff. Being checked on it should be no problem. The fact that he is put under pressure is part of the training. When he completes his training he should feel that he can handle any situation under any amount of stress. Even if most of the pressure is self imposed. If he is successful he will have to do it for real soon enough with lives at stake.