JD (like the name)
I think the use of single etops is only worthwhile if, in the example above, everything in the Canadian maritimes are below legal mins. Sure, you could use EINN to get all the way across, and it's perfectly reasonable to say that's dumb. But, by using EINN only, wouldn't you (most likely) be caring a whole bunch of fuel to fly back across the NAT at 10,000? It would most likely not be the optimal fuel economy if you're able to designate 2 or more just to use one.
Like I said, we can do it, but almost never seen it used. usually it would be some pace in the middle (BIKF or in the pacific if it's the day PASY has good weather). It's sort of a last resort before cancelling.