You then have to ensure the flat side of the blade pair meets without a gap. The gap, at least when I’m sharpening wood planes with a chip breaker, allows mater

You then have to ensure the flat side of the blade pair meets without a gap. The gap, at least when I’m sharpening wood planes with a chip breaker, allows material to get stuck which will prevent a good cut. I would imagine getting some spine caught in a gap there would cause issues. With a single blade you don’t need to worry about the back flatness as much.