If there are like to be delays at the hold then single engine taxi would seem to be worth it and all the fiddling about associated with it can be done in the queue. It is also useful when against the clock on a slot and can save a minute by starting just one engine and releasing the engineer then immediately starting the second engine with the taxi clearance.
What I don't understand is why so many are so keen with a standard 10 min taxi for all the reasons mentioned above.
Taxi in shutdown pretty low risk.
Just a couple of thoughts in general. With SET, taxiway slope, crossing active runways, taxiway condition, complex or narrow taxiways, heavy ATC, aircraft weight, etc, etc all have to factored in. SET is not suitable when thrust, control and distraction issues are likely.