Dark Knights are in kinda the same boat as they don't have their own TP regen skill or TP saver, like Shield Swipe. There's nothing wrong with upkeeping a high-damage rotation; just realize that you can't be using that rotation 100% of the time. With that said, there are usually some down times within raids/bosses-in-general where you're not doing anything or just dodging. That downtime can be your TP break if you're not using your support actions like Izsha suggested.