Take a promod for instance. It doesn't exactly take 2 seconds to get out of it. You are packed in there between tubing,etc. I think an impact in a 250 mph pass can affect your ability to get out of the car more than one at 80 mph. I think that's why the burn rating (seconds) is done the way it is.
It's a lot cooler than being on fire.....I know some guys don't want to suit up like a top fueler because the "only" run 180mph in the quarter lol. These guys are running close or over 200 to the 1/8.
In all the various things I've done and ordered for business or pleasure, machine shops have consistently taken 3x longer than anticipated. I mean really has anyone ever got something from a machine shop on time?