FWIW, I don't view the shotgun as an ideal home defense gun, I think the handgun is. Using the handgun frees your other (off) hand to do things like hold a flashlight, turn on a light switch, open a door, fend off an unseen attacker, etc. Plus I personally feel that a shotgun is much easier for a bad guy to take away from an untrained user. In some training videos that I have watched, Massad Ayoob refers to the shotgun as artillery, to only be used after you have retreated to your safe room and "counted noses" (accounted for all familty members), due to the possibility of injuring unintended targets such as family members. He also makes the point that the shotgun excels at shooting through things in an appropriate situation, such as furniture etc, if the bad guy is using cover, so the shotgun does have a place in the home defense plan, even if it's not ideal as a first response.
Having said all that, and to try and answer the original question, I train quite a bit with my shotgun (used in addition to a handgun in my home defense strategy). I practice manuevering the shotgun (short barrel and shortened buttstock) in confined spaces, topping off the magazine from a ready firing position and single loading the shotgun (pump in my case) from empty to get back into the fight. All of these techniques are available in videos online and should be practiced until they are second nature to you if a shotgun is part of your home defense plan.
Some other random thoughts on using a shotgun for home defense are to mount a flashlight on the gun (it's hard to use one in your weak hand when holding a shotgun) and to keep extra ammo ON THE GUN. Keep the extra ammo in a side saddle or a butt cuff, but keep it on the gun as you WILL forget to grab it in the event of an emergency. I also don't recommend a sling on a home defense shotgun. Too many things it can snag on in a typical home.
Just my opinion, based on 20+ years of experience using a shotgun for home defense and security work.