What I've always taught my students is that all pre-arranged movements are stepping stones to spontaneous movements. I most certainly would not place a new(er) student against anyone experienced or not with out an arsenal of techniques that they can execute. We start with techniques done in the air, then against inanimate targets, then again someone that can move, block, and hit back. Once the one-step application has been technically developed then we work several steps such as Sanbon Kumite, Again once the pre-arranged kumite has been technically developed to a moderate degree of ability we move to padded sparring and so on and so forth. This being said, the next level becomes spontaneous action while in the midst of a spontaneous (and unexpected attack).