Old school - new tool.
Mill stones need periodic dressing (sharpening). Refreshing the furrows, lands and feathering increases the efficiency of the stones (kg/hr), which in turn requires less pressure and lower friction, resulting in a lower temperature of the flour, which preserves nutrients and prevents proteins from denaturing - all beneficial.
In North America, stone dressing was itinerant work. As the stone dressers went from mill to mill, the miller would ask; "to show me your metal", referring to the metal fragments lodged in the dressers hands and forearms. The greater the experience the more the metal fragments, or so it would seem. (Ironically it was more a measure of the smith who put a temper on the mill picks. Bad tempers made for brittle picks.)
As the centuries passed (swipe), mill picks have advanced in design and materials; now with hickory handles and carbide tips. The bottom right pick just arrived from Trow & Holden in Barre Vermont, where they have been making mill picks since 1890 (they made the stone tools for the Lincoln Memorial). Most contemporary stone dressing is done with pneumatic air hammers, I was trained with a mill pick and will probably continue to practice this technique. I love the continuity. Slow food, slow money and slow dressing.