I'm in the first, regular vault hunter mode, not True, nor Ultimate.
Yet using Wildlife Exploitation Preserve, and Doctors Orders mission, I went from one Lyuda, to 18 other legendary weapons and grenade mods. I even got a Commando legendary soldier class mod. So when I redo it in True vault hunter mode, that's what I'm doing again.
Note: if you purchased the relatively cheap 'Creatures Circle of Slaughter' DLC, it's in the Wildlife Preserve. You can run into that area, loading it, then immediately run back thru into the main area of the wildlife preserve, then save and quit. When you restart it, you'll always begin halfway thru the Wildlife Exploitation Preserve, so then your run to the loot Midgets boxes in the Area where Bloodwing was initially locked up, it only takes a minute.
I wish I knew this before. Instead of farming legendaries, once I hit true vault hunter mode, I started going to Claptrap's place in Windshear waste, grabbing that mission echo out of his furnace he first stood by in the beginning of the game when he brings you to his place. Then without using fast travel, nor vehicles, I walked the entire distance from Claptrap's place, to Eridium Blight, to the top of that mountain path leading to the volcano's river of lava. There you let that little psycho guy you happen upon, hit you once, being careful to not have a spike shield, or Nova shield on, cuz he's easy to kill.. Making sure he doesn't get killed by me or my shields inadvertently, I let him hit me once, then I watch him leap into the lava. Then three birds or Rakks fly overhead, dropping three awsome loot chests, filled with Purples..
Now THAT took a long time, all that walking. It's based on LOTR, from all Frodo's walking, to Golom attacking him at the last minute, on top of the mountain where he had to throw the ring. Then Gollum falls in the lava. Lol This game has lots of those hidden movie themes..