3:12 to Yuma, if Yuma is freakin' hell

Blog posts aren't supposed to make you crap your pants, but this one from the L4D blog will turn your bowels to water. The whole thing is well-worth reading, but for the attention deficit monkeys, there's one sentence that tells you everything you need to know:

Given the extreme pace of Survival Mode, the number of zombies killed in a single round often outnumbers an entire campaign.

Consider that last night, Frisky, Bone and I dropped just over 2400 on "No Mercy"/advanced in about 75 minutes. A round of L4D's survival mode is designed to last about 10 minutes.

10 minutes my ass.

The post is accompanied by an informative graph, which provides some nasty insights:
(click to enlarge)

The red curve is brutal. The way I read it, at about the 3:12 mark, a Boomer, Hunter, or Smoker is going to spawn in every 4 to 5 seconds. At that point, you'll have already faced 4 or 5 horde rushes and 2 tanks, in addition to all the specials wandering in at extremely regular intervals. And Valve haven't mentioned yet whether we'll find any witches in the arena. Dirty.

Extremely regular. Is that like extra-medium?