I'm pretty sure Bungie didn't intend for people to farm these non-stop for hours. Why? Because its not fun, as you discovered. I did enough to complete my bounties and a couple extra by helping friends and stumbling across them while doing other things. Still managed to get one key. One of the things I learned about Destiny a long time ago was to not get caught up in grinding/farming activities. I never spent much time at the loot cave and had no interest in doing these Wolves public events for hours on end. That's a great way to burn yourself out on the game.