this is really where i come from as well. dream shards aren't worth much these days, and since i've already got my enchanting maxed out (and three stacks of dream shards in my bags) i will just say at the the start "I can DE if you want" and just greed roll everything. that sets the pace for the run, and i'll DE anything that I get greeded or otherwise. unfortunately, that leaves some funniness at the end when the one purple drops from heroics. most people don't usually need the upgraded purple but everyone greeds anyhow because "zomg its purpel epix". if i ended up with two or more dream shards or one abyss crystal, i'll say something like "roll if you need a shard" or "whisper me if you need a shard" and it ends up not mattering much because a) i've got plenty so i don't mind giving them out as everyone "proper and due loot" from the run, and b) because most people don't care enough to roll on dream shards anyhow, and if they do, i'll gladly give them one or two.

abyss crystals are a little different. at the start of 3.2 and reg TotC farming, I DE'ed everything and everyone got a crystal at the end. a week into it though, i realised that the market was saturated and it wasn't worth worrying about anyway. i also stopped running the 5 man Trial a few days after its release anyhow (thanks for making it interesting for a few days though blizz).