Fiver,one of my boys when shooting his Hoyt(don't get me started) recurve can NOT keep his bow arm steady,at the moment of the shot.ILF limbs,47# so it ain't an overbow situation.We all kid him about his mis-spent youth...nuff said.But,he regularly is a front runner in competition.We all just look at him and wonder,how in the heck is he even hitting the blooming target....then,wooosh,another 10.It just ain't right,haha.
So,back to CB's;shooting off a bench is one thing.The process is aided by,hopefully well engineered,rests and a stock that repeats well....doh.
You're at an advantage because of your shotguns....and you already know this but,because of the swing involved,you never have to work on a "steady" support arm.Benchwork is fine for rifles but if folks would practice a bit more on offhand they'd quickly realize,how important a steady support arm/cheekweld is.This is where fit manifests itself.