Summary: Shooting from a laying down position such as when hunting from a laydown blind can throw off a lot of hunters. I think part of this is because the incoming geese look so much farther away than they really are and that a hunter can't swing on crossing targets as well.
Another issue when shooting from laydown blinds is that you can't pivot like when your in a standing position. To help overcome this limition it's a good idea to rotate your blind slightly to the direction of the shoulder you mount your gun too. So if your a right handed shooter rotate your blind slightly to the right on your next hunt. This will allow you to swing on geese or ducks that are to your right much easier while still allowing easy swings to take a shot at a goose to the left of your position.
When I first started hunting from sneak boats and laydown blinds I was really frustrated with my shooting. But like most things in life, practice makes perfect! :-)