Warren in Lancaster, PA
I think you can safely over cut a small amount on the inside, but in the end cutting the corners out is done with a chisel. If you remove what you can from the saw cut area you get a little guide surface to register the chisel. I think this is one of those cases where a flat, single bevel does better, because it makes a better wedge to push the waste out of the way. Also the chisel does not get stuck in the cut as readily.

If you look at better and best you will probably see more full dovetails than half tails. in this application.