I wanted to change the boxy look of the Sr without hurting it's flight characteristics. I started with putting the wing tips on backwards and flat on the table. I the realized there was enough scrap balsa in the kit to make some half ribs for the wing. I then added more shear-webbing and diagonal bracing. No I don't think it's needed, thousands of Srs have been built and flown without it, I just wanted to do it.