yea it goes out quite a bit, but you prioritize it for a few specific knockbacks. the 2nd tank add in phase 2 is the one we usually use movement abilities (blink, goblin boots, disengage) because right after you all get pulled into the tank dispell a bursting dreadflame goes off and it can 1 shot people on mythic. if you use it there usually you'll have it up by the end of the fight to cheese an obelisk knockback as well (the fight generally takes ~11-12minutes for most guilds) we lust on the pull and had our lust up when he was at 15% for time reference.
yea i agree, some of the fights are just not done well in tomb. ive raided from vanilla through icc in wotlk, and then casual until late wod and the worst bosses ive ever dealt with are mistress and KJ (both equally terrible, and for different reasons)