I think having frequent mini tank busters and possibly a bit of rng element involved might incentivize the use of tank stance. If the big damage spikes come every 1-2 minutes we can stack several mitigation cds, but if the damage comes in smaller spikes spread throughout the entire phase/encounter, we can only spread our cds and if that's not enough mitigation, we'll have to go into tank stance. Back in 3.2-3.3 I think tanks still went into tank stance in a8s phase 2 and for the final punch + beam combo without LD/HG, in a12s at low ilv tanks might go into tank stance for the general's might add in phase 2 (I usually started in deliverance, do my berserk rotation, go into defiance and pop unchained, before going back into deliverance with vengeance and thrill up), though with exceptional group dps it's no longer necessary since the adds die so quickly.