My son has never mentioned that R’ Tzvi checks his seforim or that he feels any “pressure”. He came from a Telzer structure here in the US and was able to adapt to R’ Tzvi’s derech.
Yes, his post shalosh seudas drasha can go 2 or 3 hours but I don’t believe that the bochurm are required to attend.
As for locking the door when R’ Tzvi starts shiur….it forces the bochurim to come on time.