From a hand tool perspective the housing is where the excess is removed. I don't spend any time trying to make the housing just right, usually guess at the scoop and when I check it with a straight edge it is grand. I sure don't want it high.

BTF, how old it your oldest frame and have you been back to see how tight the joinery is holding? I see gaps on certain joints, most likely related to species and twist, spruce is usually the worst offender.