Orthotics or other footwear inserts including a set of separate and incrementally different inserts sized and adapted for a right and/or left foot. One such insert in said set has a first corrective structure and at least another such insert has a second corrective structure. The second corrective structure including at least an incremental change in one or more of curvature, thickness and firmness of at least one sidemost portion of said insert in said set as compared to the first corrective structure and a corrective structure of each other said insert in said set. The inserts in the set have a progressive sequence based on the increase or decrease in one of the curvature, thickness and firmness, are adapted to be worn one at a time for a period of time sequentially based on the progressive sequence and also include at least one internal sipe.