If your turning at .004 to .008 ipr, each tool would take .002 to .004 ipr so you have up to .002" of wear before the "balanced" part would fail. As one edge starts to wear, the other wears as well, prolonging the tool life. Mind you, if your using say a .015 tnr rougher and a .008 tnr finisher, you could use that differance(.006) in X for a good surface finish with the finisher, but the bulk of the stock is removed with both tools using the same force and chip load. Any thoghts?