How exactly are people getting long run-times?

I'm running 3S packs on my 808 with a MMM 2200Kv combo. I can get more than 20 minutes from a 8000mah pack, which weights 560g. I've got some 3S 5000mah packs that are 100g lighter, but i haven't tested them yet, i think i would get around 15 minutes.

I couldn't be happier with it, 0 problems. I know people running 4S and over who are always complaining about temps or runtime...most of them said 3S wasn't a good idea.