The way you present your thoughts in this post show that you think me using an additional shard to dot a secondary target is going to severely hinder my single target damage is pretty silly. Considering that in T14 gear you are better off pooling shards for DS the likelihood that you will be near shard cap is high. Overlapping Haunt is no more or less of a waste of DPS than it is using that extra shard of a full set of dots.
Do I agree that "padding" on a fight where you are nearing a DPS check is not needed? Yes. Do I feel that in its current state of shard pooling it's more beneficial to not cap out your shards nor overlap Haunt and is better to use a SS:SB than waste a Nightfall proc? Yes.
With T15 extending Haunts duration during DS it will just make shard pooling even less of a hassle since you won't be "required" to pool 3+ shards which just opens up more Nightfall procs for you to play with. What else are you going to use them on? You have two options; chain cast Haunt, SB:SS or waste a proc and just overcap. Pick your poison; I know my choice.
---------- Post added 2013-03-06 at 08:58 AM ----------
I could go on but I hope I painted the picture with just that.