Cat-related incident left a roughly 12 inch hole in the hallway. For something that big do I need to cut in a backing board and screw a patch to it, or can I get away with a self-adhesive mesh patch and a few coats of compound?
Feather the final coat way wider than you think (12-16 in) so the hump vanishes under hallway lighting.
Seconding the backing board. Mesh is great up to 3-4 inches; beyond that you want something rigid behind it.
At 12 inches skip mesh-only — it’ll flex and crack. Cut a clean square, screw furring strips behind, screw in a drywall plug, tape the seams, three thin coats.