darlgael; What you wrote suggests to me that there are at least two ways of using an patterning board to determine pointing as opposed to patterning characteristics.
The only time I used one I carefully sighted down the rib to aim. The purpose being to know where the gun was shooting in regard to where it was aimed.
Anyone feel free to correct me if I am wrong, but what you describe seems as if the idea was to determine where your tri fit was pointing in comparison with where you looked, which I understand is what I am supposed to be doing as opposed to aiming at clays.
Although I will not be using a tri fit, I will take a lot of paper with me and try to discover both my POI when sighting to he POA, as well as the POI when looking at the the POA, if that makes sense. I might also give it a go with both one eye and two.