Yea I had also read that similar to crit weighting with ambushers becoming redundant at some point, same for sighting.
I'm not sure if that meant sniping (and so an increased weighting?) or just that skills at a certain point don't really miss much and so its wasted on the item (cap-postcap).
Maybe someone can do testing or point out where for Tenser.
I checked Art of the Bow but same limited for sighting thresholds:
https://gswiki.play.net/Art_of_the_Bow_(guide)#Sighting