Snakeskin won't hurt or help the bow's strength. It is just cosmetic. You don't really lengthen the draw. 28 inches is the standard at which most draw weights are measured/posted. Depending on the bow's draw weight at 28 inches and its length, it will gain about 2-3# per inch for each inch drawn past 28 inches. If you have a linen backed bow, it's likely an older wooden unlaminated bow made in the 40s or 50s. IMO, such a bow, unless it is at least 68 inches long shouldn't be drawn beyond 30 inches. In short, don't bother putting snakeskins on it because at 31-32 inch draw, it will break, maybe not right away, but it will break.