Well brosky
How I can explain
well in cabin fever you make a room with only 4 mans and play only 3 or 4 rounds
In 1 hour you gonna get more exp that is you game a complete game expending the same time.
Thats one of the way, there are lots of ways
Get a bunch of people together. Start a QR room. Zombies win, Humans Win, rinse and repeat till end of game. Get massive XP. Continue until you rank up.