Run a two gun match at a local range where your average homeowner/fudd wants to get their feet wet running shotguns on poppers and plates. I have. I facepalmed more the Jean Luke Picard.
It won't take long to realize a shotgun requires far more "skill" to run than an AR.
Unless you live in the Biltmore House, typical ranges inside a home, mean your shotgun is a 12bore rifle.
Most off the shelf buckshot isn't well suited to inside a home. It's heavy recoiling, heavy loads.
A shotgun at 20 ft must be aimed every shot, and recovery from recoil can be an eternity if you miss.
A good home defense load should be T-#4 buck, 1ounce, light target. Much easier to handle fast.
You MUST train with a shotgun just like any other weapon, and I'd say more so.
I've seen people shoot their shotgun in competition that thought "hey, it's a shotgun, can't miss".
It's ugly....real ugly.