Yeah, I don't think Spencer's mentality is any different from those other wrestlers. The decrease in scores after the first 2 periods has more to do with physical rather than mental conditioning.
Did you watch his NCAA matches from 3rd title run? He had tough matches with Schroeder, Hildebrandt, and Courtney. All lasting 3 periods. None of which featured any 3rd period gassing. That wasn't because Lee suddenly decided to not be a "bully", but rather because he had no acls and had to adjust his style and pace accordingly