I suppose the shanks on different brands might be a little different but I’ve always felt that the Nichols sweeps on our Krause finisher actually run up hill (point higher than the heel) just a little bit when the tool is out of the ground/no load on the shanks.  

For the most part they always wear very evenly.   The exception to that would be sweeps that one side is behind a tire but the other side isn’t.