The problem with trap as shotgun practice (and it is way better than no practice at all) is that you can shoot wrong and still do very well. Watch a trap shoot sometime. You will see people grinding targets despite odd stances and bizarre gun mounts. What’s worse is that because the angles in trap are shallow, you can be very successful aiming right down the gun barrel and shooting a trap gun like a rifle. And that’s fine for trap, and for a lot of upland shooting, but not when it comes time to shoot any kind of bird that requires some lead. Then you have to learn to get your eyes off the gun barrel, because if you’re aiming your gun at a crossing duck or dove, you’re going to shoot behind it.