Many times in games, people want to settle a roll off while others are still fighting so they can save dom or leave earlier. Often, this results in rolling onto someone who is still fighting and possibly messing up their game. Instead of having both people roll, it makes much more sense to just have one person roll and to compare it to an average roll. It is likely that one of the two players can roll on a neutral player (one not still fighting), and this can be done with a much smaller stack. An average roll of one die is 3.5 (though it is never rolled :P), so averages based on #dice are:
1(3.5), 2(7), 3(10.5), 4(14), 5(17.5), 6(21), 7(24.5),8(28).
It will end games quicker and not screw up the games of players who are still fighting.