With a few days shooting clay birds I went from never using a shotgun to hitting 7 out of ten. If you have an eye for it, it doesn’t take long.
Pistols like a Glock only have about 3 or 4 inches of separation that greatly exaggerates any minute deviation of barrel movement.
Shotguns are easy to master, and can easily show results like you listed.
pistols, on the other hand, take years to master and require countless hours of practice and instruction.