Aside from parsing it's good to know if you're doing your rotation correctly. The nice thing about this game is that every dps has exactly one rotation and only one optimal way to play them with no RNG (outside of procs of course). There are guides here on the forums that discuss the correct rotation. There are a few other ways to know if you're doing as much damage as possible and that's the things outside your damage rotation as a nin, are you keeping huton up? Are you keeping all your DoT's applied? Are you using your oGCD abilities that deal damage? Are you keeping up your slashing debuff if no warrior is present? Are you doing your positional attacks correctly? Are you using your ninjutsu for damage? Suiton for your Trick Attack/Sneak Attack? Doton? Raiton? Etc.