I never heard of an "official set" of one-step sparing techniques. In our org we lay awake nights to make up our own...then steal all we can from one another. The GM and BB's only intervene when one set or another look to be wholly impractical.
It's like the GM walks up and asks, "Okay, so you hit him in the head twice already. No need for a third. He's already fallen down by now." Alternately, he might ask, "If the first two failed, why go for a third?" That sort of criteria.
He got me for following up an upward elbow strike with a downward backfist. Same reasoning. If my elbow connected, the face won't be there anymore.
Anything goes, but it's gotta work. I like to toss in a few things left over from when I used to take Hakko Ryu Jujutsu. If it works, our GM is okay with it wherever it came from. Only the 22 basics and forms are pure TKD so far as I have yet observed with all the rest being widely eclectic. I like it that way.