Something else that hasn't been mentioned is the DoH/DoL responsibility to do emnity resets whenever the NM issues new orders. This is what disperses the crowd from wailing on a single target and is most critical when they all start dashing to a specific cart.

I'll normally play DoL and take on this job with one other DoL. During the first 10 minutes we'll do attack down and a bit of poison where permissable (no unique-weapon mobs up or about to pop). During the 2nd ten minutes, it's still attack down interspersed with emnity resets, since the new orders come around about every two debuffs - you can get the next one ready the moment you've handed in your 3rd red pot. You probably want to make sure your DoL are doing this.