If you DAGS on patching sheetrock, you'll be amazed at the amount of
A professional repair:
cut hole to a "regular" shape, like rectangle.
cut scrap of sheetrock 2" longer and wider than hole, or slightly less.
from backside of that, remove 1" all around, of paper and gypsum etc.
You've got a 1"-wide paper flap extending all around "good" side of
sand around edge of opening in wall
apply compound generously to back of patch "flap", insert into hole,
and use blade to remove that compound as possible.
continue with compound coats, etc., etc.
This can make for a very strong, undetectable patch.