I don't think bareshaft tuning is the best way to deternine centershot. On the other hand, I think it's essential to use it before tuning for centershot, in determining proper spine. I start out with an arrow that is slightly too stiff and too long. Then, with my draw weight where I prefer to shoot, I start trimming 1/4" from the arrow while bareshaft tuning, until I have dynamic spine perfect for my setup. Once I get real close by trimming the shaft, I finish up by fine tuning draw weight until the spine is exactly correct.

This method requires that you not build your arrows until you are done bareshafting one of them. To do this correctly, you have to actually fletch one to where you think they'll end up (experience will tell you this). You need one fletched arrow to use as a comparison to the flight of the bareshaft arrow.