After using a trim router to remove the bulk of the material from your hinge mortise, use this corner chisel to dress the corners in the blink of an eye.
Position the chisel over the corner, tap the spring-loaded chisel head with a hammer, and flick or cut away the waste material and you're done. Once you get used to using it, it'll leave you with a perfect corner every time. It'll cut up to a 3/8" corner and up to 5/8" deep.