On the one hand, a proper endgame is a rare occurrence (it happens more often on certain maps), so I don't see the point in introducing a timer just for that. In those rare cases when the endgame does happen, why not take the time to think it through properly? After all, the endgame doesn't take up a large percentage of the game. I don't see any harm in spending 30 minutes on the endgame after a 5+ hour game.
On the other hand, there are some players who like to open various calculators during a battle, calculate everything cell by cell, etc. This is, of course, not very good. But still, is it so annoying that it needs to be accelerated in every possible way?
P.S. If you play Tournaments, you don't always get to choose your opponents, so let's start giving black marks for dragging out the battle and bad manners, and ban them from tournaments, which will give the admins more work. I can name a couple of internet warriors, even from the old-school community, who I would ban without hesitation.