So what is the optimal duration of combat? It's kind of a vague question but something a couple of folks have mentioned is that the current martial bonus is primarily there to speed up combat.
Two things spring to mind:
If I need to up player damage to speed up combat, then probably the combat in question isn't worth taking the time to do in the first place. If the combat is significant enough, then it's worth the time. I know we hit an extreme in previous editions and we should expect combat to be shorter, but all the same I want my fights to matter or I don't want to bother fighting.
If the numbers are fixed such that combat is almost always 2-3 rounds (as it's been stated in a few places), that creates a treadmill feeling far more ingrained in the game than freely scaling numbers-by-level ever did. That means that no matter where my character is, what level they are or what they're fighting, a given combat will last 2-3 rounds. I could be fighting a pack of goblins or a pit lord and it makes absolutely no difference whatever.
Being certain that a fight will be quick is just as bad as being certain the fight will be lengthy. I would love to see more variety in the beastiary and a removal of some of the really weird system patching going on to force combat into this duration.