The idea of a comfort zone is a powerful one. Carl Froch offers some fascinating commentary in the video in this link:
I could do 15 or 20 rounds in the gym at my own pace against guys lighter than me or not skillful enough to match me technically. But I was sparring with a guy who was a Cruiserweight/Light Heavyweight and after 5 or 6 rounds I was feeling the pace, thinking “what’s going on?”
We’re also told that Wladimir Klitschko’s trainer has been concerned with the pace of training and WK pulled rank, basically saying “it’s my gym, I’m the star, I dictate the pace.”
Doesn’t bode well, does it!