Dawdle? Ever since you learnt how to jump off the roof of the first level of No Mercy (and live) it's all you do
Jump, heal, run, set off car alarm.
The rest of the people have to deal with the horde (I know that one as I got kicked for leaving them behind doing exactly the same.)
No Mercy is more fun if you have one guy call for rescue and everyone else stays down the ladder
I quite prefer Dead Air and Blood Harvest though the latter is a pain in the bum when you have a team that insists searching every room...find the new guns and get to the end. If you find molotovs, keep them for the tank.
It's like in No Mercy when you press the button to turn on the extending lift thing to get to the roof; why hide in the corner when it's far easier to get to the roof and peg it to the next room? All the horde does is slow you down and take some health off you.