Mopar specified a 15-45-70 3angle in their racing manual, for a reason, it worked & ran better. there are as many combos of angles, numbers of cuts, radius profiles-top only-
bottom only-or both sides of the seat as your brain has the imagination and the patience to try. I don't buy that "sharp edges" argument, sometimes sharp edges work better,
serdi/sunnen/goodson 3D, etc. offer some accuracy & consistancy but most of all efficiency.