Sometimes that will work - I've done that. Sometimes I just made more holes. Not sure why I would leave a gap big enough to stick my hand in. I make the back so there is maybe 1/4" leeway to slip it in. HOnestly, I trust a 1-2" circle of liquid nails at each end over a drywall screw that is only going into nothing but a piece of drywall. YMMV.
Gotta go: time to make an entrant into the poop thread.
What ?- it's a trademarked word that became like BandAid. nothign to see here.
Settle down Hershey syrup man *That was awesomely funny.
The backing pieces aren't to patch the hole. They're like "framework" to screw the piece to that does patch the hole/come flush with the face of the wall.