Throughout my 991 hours of playtime ^{holy shit get a life} I’ve seen many divers using the HMG at the lowest firerate possible, sometimes at 600RPM when just picking it up from a corpse or something, but people using it at 750RPM has been a VERY rare occurrency, at least as far as I could tell when I wasn’t busy surviving.

Obviously if you pick it up because you have no other option you’re going to go for the less uncomfortable setting, and if you’re trying to shoot down a gunship you won’t go Rambo with it, but other than such edge cases…

… what gives?

Why would you choose the ohfuckohshitohfuck stratagem and not use the ohfuckohshitohfuck setting when five hulks are chasing you (A.K.A. the ohfuckohshitohfuck situation)?
As far as I can tell THE appeal of the HMG is its insane DPS.