Crazy. I guess you have enough DPS to kill the first one easily in one cycle (with ~10 seconds to spare on the clock) the buff isn't going to be that noticeable. If you're down to the wire on the first one it's definitely not worth kiling her.
I was with LT's group specifically and most were 290+. we tried killing one and then killing the other the second round but only got her to halfway before we ran outta time. pretty major buff from our experience. I'm guessing all 300+ with super strong weapons won't be a factor. I wanna try taking them all down in one round.