There is a myth that Doug Harvey at one time played all 60 minutes of a game when the Habs had defence injuries. It is not verified, but some people say it happened.
I wonder today... if say Karlsson could actually just play the entire game and pace himself enough to be able to not be uselessly tired at times.
On an aside. I remember one Sens 3-3 OT last season. There literally was not any opportunity to change for almost 2:30 of the game for the Sens. I remember Turris and Hoffman almost dying on the ice because they were so tired.
Obviously 3-3 is way more tiring then normal 5-5 play. And the players were not just staying on the ice, they had no chance to change.
Maybe I am misremembering it a bit. Maybe it wasn't Hoffman but it definitely was Turris, and I think Karlsson. And I can't remember the outcome of the OT. Just that three guys, and definitely Turris was one of them... had to play 2:30 of OT straight. And they were so gassed. Like at the end they were just done. Like they did a triathlon.