In fact, I seemed to get absolutely terrible drops, and I began to think there was a conspiracy against me.
Then someone (who had 3 obsidian shards dropped during the run, I obviously had none) told me that the chance of a drop is based on your experience. I thought maybe he was right for a while.But tbh, I doubt there is any such feature; I bet it's just entirely random. An area will have a list of possible drops or mods to put on stuff, and a chance for each of them, and something is chosen randomly based on these chances and then randomly assigned to someone in the party. Because of how randomness works, you could go to UW over 100 times without a single ecto drop ever (happened to me - unlucky eh?), or you could get loads in a row (happened to me more recently, after finally getting my first ecto).
Now I drew the conclusion that the person I mentioned before was right, and I had started getting them because I had more experience, but really, whatever happens, you could draw some conclusion from it, it's all just conjecture. The fact is, you don't know. Unless you empirically conduct research into it, you could be seeing things that aren't there.
Edit: If I'm right about it being entirely random, and based on a list of chances (e.g. 5% chance of ecto, 10% chance of perfect mod, 20% chance of within 3 of a perfect mod etc), then your best way of getting good stuff is just to play more
