How much time did you needed to do this achievement ?
Sorry it took so long to reply. I did all but Putridus in about 2 weeks last June, and probably because I bragged that I could definitely get Frostbitten in that span, could never get Putridus. I camped twice a day for a month or so, and always got beat by horde hunters. I rarely play my hunter, so it's probably a miracle I got him at all.