There a few pulls you can use buffed Abyssal drain to literally self sustain (first pull on platforms in factual) ton of mobs that don't hit all that hard.

But on topic. Imo parry is garbage on trash mobs they won't live long enough for it to really matter you have Cd's for big pulls.
For bosses again you have Cd's for tank busters parry again is not worth stacking. So parry while yes is free mitigation it's mitigation your healers aren't banking on.
As for steel cyclones it's free hate and free damage. Unless I need inner beast for the extra damage reduction I use it everytime I can on big pulls.