Since we are not shooting long distances, many times we take long gun practice lightly. We need to spend as much time training with the rifle and shotgun as we do with our pistols. Once again, a good practice session does not take a lot of ammunition. One shot drills will do more for you than blowing through a bunch of ammunition practicing sweeps. One of the best things that you can do is to practice one shot drills. What I mean is, practice acquiring the weapon and getting on target quickly with the front sight. Most of your time with the long guns is probably lost getting on the first target, not in going through the sweeps. This allows you to have a very productive practice session without using a lot of ammunition.
Also, when you have a miss on the shotgun if you shoot the double barrel, go ahead and load both chambers for the makeup shot. Your muscle memory is used to loading two, plus it takes no more time to have an extra round if you miss again. Also, there is no danger of hitting the wrong trigger.
Check out this video for some effective training tips from a top shooter