Doing a full pull until the first boss, full pull until the 2nd boss, full pull until the third boss can finish the dungeon in roughly 5-6 minutes with decent dps. Same story with Haukke HM or any number of other dungeons.
Even through full pulls, I have never personally experienced such a huge time gain. In most instances I experienced we have actually been wasting more time than saving it by pulling 12+ mobs. But my main point isn't really about efficiency itself but rather annoyance. I don't personally particularly care if the dungeon that should take 6 mins ends up taking 15 mins, but assuming you will queue in DF with pugs and get a 6 mins run is rather...strange...just like I think queueing for titan EX and expecting a 1-shot kill is strange.