You are so utterly confused i really don't know where to start - and you are SO confident in what you are saying! How DARE i suggest that a skilled DK will time their DS to maximize healing and reduce healing required - HOW DARE I SAY THAT!. Honestly, you are just confused. Very, VERY confused.
And fyi, the reason BRM will sometimes take a while to die is that stagger cannot kill you (unless they changed it) but any single other hit will.