Just as an aside for dungeons it can be good to use Provoke as a way to trigger the script of enemies from a further distance. So, for example, getting a boss to come to you sooner when you have a combo going, or getting enemies to bunch up sooner.

But like, in combat, single target, unless it's to get yourself back to the top of the enmity list you don't have a reason to be using it on something already fighting you.