It sounds like there are two camps here.

Those that like plans, a setup, and a final execution of the plan.

And those that like improvising.


L4D1 definitely caters to the first group, as thats the only real way to take down the survivors (the grand slam).

L4D2 caters to the second group: between the huge permutation of SIs that might spawn in, the new kinds of ways they might hurt you, and the new deadlyness of the CI, its chaos all the time. There's no time to have formal plans, you make it up as you go along.