Its accurate to the best of my knowledge...my knowledge being based on availability of other tools and fretboards at my immediate disposal, and the choices available due to the dual set (7.25 - 20). It is smooth and even across its width.
My only issue which I realise now post the purchase is that i should have opted for the understring version for a little more cost. Anybody who wants to make their fretboards regular will be anal enough to want proper string radius too. This version, although doable, cannot help in accurately setting the height of the wound strings. Particularly more true if you are into heavier bottom string gauges.