In the form in which the chess timer is currently presented (as in the BT example), it is not acceptable for the game as a whole, because strategic battles are penalized by time, when in essence they should be encouraged. There should be no countdown in battles, so it's simpler to set any time in the SoD timer.
Which mega-super strategic battles are you referring to — I hope not battles like 1 Harpy vs 20 Frenzied Behemoths or Ballista without the skill vs 100 Skeletons? ;)
For all other "simpler" battles, the current time of 5000+400 is more than enough, at least in the first month of the game for sure :p
P.S. I also forgot about battles of a certain class of Heroes, who sit and move the mouse around for half an hour in every battle! — as if not to lose an extra skeleton. :D