In all honesty I can count the number of times on my hand that a fight lasted that long. The reasons for that were either:For me, unless the battle is truly epic (end bosses, etc) 10 rounds or longer is too long.
1) big boss fight,
2) a lot of space (like 200 by 300) area we were all moving through, trying to complete a certain goal while dealing with a ton of enemies,
3) dice being so utterly bad everyone was whiffing.