I chain my pulls together.

Example, mt gulg. There's some fuckhuge pulls in there you probably don't wanna get all together unless you're a coordinated tank/healer. If that's the type of pull, I'll usually pull two of the groups ( 3 if I trust the healer ) and keep them still, AoE'ing for a bit, if there were say, 12 mobs there, and only 3-4 left, I'll proceed to pull another pack, stop briefly to AoE combo them and let dps do their rotation to keep stacks, and pull the last group before coming to a complete stop.

More AoEs hitting more mobs for your GCDs = quicker everything dies at once. Usually I get 2-3 comms at the end of the run and our dungeons never last long at all unless DPS is just poor on the boss fights.

Also food for thought, some tanks may pull a group, see it isn't stressing their healer at all, and move to pull more. As for the running them into dead ends before the door opens, not a clue, maybe just instinctive to them to pull more but forget the door is closed