Something that helped me shim my Benelli 28ga was the Garmin Xero S1 on the trap range. Set it for Practice/Custom/Station 3 and lock the trap to throw straight ahead. Shoot 25 rounds.
For each shot it will show you this: It's a clean break (good hit), the center of the shot pattern was 7 inches high and a bit right of the clay which broke at 30 yards.
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It also gives a lot of other info, like reaction time. This will tell a lot about accuracy when shooting quickly or slowly. The green lines are breaks, reds are misses. It even gives velocity on the loads; helpful if you're a reloader.
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My club has one and it rents for $20 an hour. I think it's a bargain. In my case, it showed I was consistently putting the pattern low on the target. I was breaking them but I was always low. Easy job to adjust the drop up to move my eye up. After that I was putting the pattern pretty much right on the target. Took the gun over to the skeet field and broke 23 with it and solid breaks. Pretty satisfied.
YMMV but I found it more informative than the pattern board for adjusting POI.