The shotgun point is a good point, but I think I would still just mount it and shoot it first a 10, then 25, 50, and finally 100 yards. With a good shooter and scope, I think the 10yd and 25 yd work could be done with 1 shot each, YMMV. Maybe 2 shots at 50. So, to sight in a shotgun initially, I would:
Shoot 1 at 10 Adjust scope so the shot would be 3" below POA.
Shoot 1 at 25 Adjust scope so the shot would be POA.
Shoot3 at100 Adjust scope so thegroup's centerwould be POA.
Shoot3 at100 Confirm POA = POI
Shoot 3 at 125Log POI
Shoot 3 at 50 Log POI
Shoot 3 at 25 Log POI

That s kind of a minimal effort IMO for knowing where your hunting load is and sighting in, but we are way off topic, it seems![:'(]