Refinement is fine tuning the practice after the basic technical model has been mastered. When that is robust, then and only then should you think about looking at attending to the finer points. Often, we are in a hurry and try to do this too early in the process and the whole technical model erodes.
Refinement does not have to pertain to just technique or skill it also can refer to development of physical qualities. Initially the athlete will begin with global attention to all qualities, as training age accrues then it is possible and in fact necessary to begin to refine the methods to be more specific to the sport and athlete. Simply refinement follows repetition in the development of the athlete and refinement is based on mastery of the repetitions.