Yeah they definitely are not... I was farming all last night and didnt get a single one.
If you want to farm planetary materials however that seems the most fun way because you get a good amount as well as other stuff. Since I havent played in forever I was actually pretty much empty on all of them and so it worked out for me that way at least!
OMFG NO! I don't know what Bungie was thinking giving us planetary mats and stupid synths. I am overflowing with those and you can't delete the damn synths. I'm wondering now if I didn't get any keys (after opening at least 40 chests including doubles) because I didn't have any slots left in my consumables. But does it show up there or in the materials area like the Trials coins do? And more importantly, do they overflow to the post? anyone know?
By the way, I'm well over 1000 hours into this game and I never realized there was a daily Crucible match until last night . What did it give for rewards before the Trials coins? Then again, I ignored Crucible entirely until a few Iron Banners ago and then I only did that and not regular Crucible.
So I was farming the stupid chests and got so many blues on one character I overflowed my postmaster and lost a couple of exotics and other items I had been saving there. So I decided now that each time I farm I will clear all but 2 rows by simply deleting the blues. And then I have to make myself return after maybe 2 double-dippings since I'll usually be close to full again by then. I'm also using the telemetries I had held on to for so long even though I have no weapons to upgrade. And I'm just using special and heavy synths whenever I can. And I'm deleting most of my planetary stacks beyond the first 200. It was freaking stupid of them to cap those at 200 while other things (like weapon parts) can go past 1000.
I do have 1 or 2 legendary engrams to decode at least. I got one yesterday that was an "old style" engram because I was able to decode it (turned into a helmet I crushed). So not all the stuff you get from the chests are DLC engrams.
So apparently you need these keys to open a guaranteed exotic and/or legendary drop at the end of the Prison of Elders? And also you only get one for free - the rest you have to get through this ridiculous farming method?
Last night I redeemed all my Vanguard and Crucible marks and bumped each character up 2-3 ranks in their factions. I got the Nineveh shader for Future War Cult. I'm not thrilled with that one - I like a lot of the rare ones I had to delete to make room in my Vault better. But the awesome thing was that I got the Fermi Solution ship from Dead Orbit. Check it out on my Warlock when you get the chance - it is pretty sweet.