Unchained, when do I use it?

[Krissey]

pre-50: whenever it's up and you've got 5 stacks

50 and beyond: single target = Infuriate -> Tomahawk/Overpower -> Unchained -> HS -> Brutal Swing -> Maim -> IR + Berserk -> Storm's Eye -> HS -> SS -> BB -> Fracture -> HS -> IB -> Brutal Swing -> Maim -> Storm's Eye (MT only, can replace IB with Fell Cleave and enter Deliverance before Fracture if IB isn't needed)

multi-target = Unchained + Bloodbath -> OP -> IR + Berserk -> OP spam

So I understand as an off-tank you basically probably don't need to put up Storm's Eye (The damage debuff one), and can stick to the Storm's Path to help out Ninja, and BB for the most potency combo, throw in Fell Cleave etc when DPSing.

However as the main tank, in order to help my NIN friends, how do I keep up Storm's Eye and Storm's Path and use Butcher's Block without letting any of them fall off?