I died an stupidly high number of times during my first playthrough >.> I died a lot against Ghirahim, once against Demise, at least twice against the various Imprisoned battles, most likely the Lanayru Mines at least once, twice against Scervo on the Sandship, and even once in the Earth Temple when you had to outrun the boulder.. pretty embarrassing really.
But oddly enough, I died MUCH less when I played through Hero Mode. Maybe only two times if I don't count my boss rush failures. Hero Mode put me more on the defensive, I remembered that, oh yeah, I actually have a shield, and by that time I knew how to fight all the enemies, so I wasn't dying over and over again trying to figure out how to kill them. I only used one potion for the entire cumulative final battle.