well not to bring that a$$hole back into the discussion but Zach was going full speed and playing 20+ minutes. Same thing with Ovechkin and a bunch of guys... their bodies might not hold and Kovy might last longer that way of course. I'd just like to see that part of his game more often cause his gliding on the backcheck certainly cost us a few times. And when he's going on a mission godamnit he's so fvcking dangerous he's creating a very good scoring chance almost every time
Ovechkin doesn't play penalty kill, so this is already a moot point, not to mention he doesn't play the minutes Kovalchuk does. Even Zach doesn't play the kind of minutes Kovalchuk plays, and it's debatable whether or not Zach's style of play can be maintained in the long-run.
Kovalchuk paces himself the same exact reason Brodeur paces himself. He wants to play in every situation he can, every game he can, and he wants to still be able to be effective in his late-30s and beyond. Kovalchuk and Brodeur put less wear and tear on their bodies in the way they play, and for similar reasons.