Of course, in online mode, on medium-sized maps, when the final battle takes place around the middle of the second week, you won't see that.
For example, take the "Armageddon" map: http://heroesportal.net/maps.php?user=1263 I'm also "really interested": how long will it take you to defeat 8000 (eight thousand) Azure Dragons? Will you manage it in 5 minutes? ;)
P.S. My opinion regarding the timer (although for me, an offline player, this is not relevant):
1) there should be two different timers to choose from, and the opponents should agree before the game which option suits them both;
2) there should be an option to "Stop the timer during battle".
And, by the way, do you still remember that "Heroes" is a turn-based strategy, not a real-time one? And the timer turns the former into the latter!
(Василь Симоненко. Люди – прекрасні)