One step sparring is not SD but it helps alot, this exercises taught us how to block or dodge or parry an income punch or kicks and how to counter, I think one step sparring is the prelude to Ho Si SUL (SD) and I don't know why it's practiced from blue or red belt and not yellow belt instead.
There are so many easy to follow one steps sparring to begin and this could be very helpful to hone one's skills since the begining.
Manny
That is something I wish more TKD and Karate teachers would understand and teach. Too many times I've seen people in TKD and Karate equate 1 step sparring as self defense, even their teacher call them "self-defense" techniques or even that is their "self-defense" course.
For us, meaning myself and my students and others with similar view, one step techniques are great to help one learn the dynamics of motion in a fairly easy way, and good for learning body positioning and for learning stability in their stances while moving and applying techniques, as a prelude to deeper study such as pushing hands or sparring.
After learning a few things, this is the first thing my students learn, usually starts within the first week.
One step techniques are good for building blocks for practicing new techniques and getting comfortable with some possible uses before jumping into free-flow sparring.
Why some people wait till higher belts to begin teaching one steps, I can only guess. either they want the students to have a foundation in stances and forms before letting them apply with other people, perhaps the tradition of their art, or for some it could be a way to milk the students letting them reach for that ever elusive carrot...