Makes no sense to me. If you get the broadhead/bareshaft hitting in the middle, assuming it's possible to do so with any consistency, as soon as you add fletching it will stiffen the shaft and it will hit off mark, unless you are tuning the broadhead/bareshaft to hit weak, so what's the point?
Time consuming, potentially dangerous and accomplishing little, if anything, that can't be done as well or better conventionally with less trouble. The only thing that makes good sense is to bareshaft tune weak with field tip, add fletch and then tune for POI between BH and FT by building out side plate, trimming arrow shaft, tweaking plunger or brace. Shortest route to good tune.