I am brushing up on different joinry over the holidays and am interested in notched members. I am working with V=(2Hbd(d/h))/3. Where V=vertical Shear
b=width of beam
d=depth of tenon
h=depth fo beam
H=Working Stress in horizontal shear, shear parallel to grain.

My question is about H and there is no real value for angling my notch cut in this equation. Is H total load of member divided into half? And do I compare my answer of V to the Shear in psi. ie White oak of 1250.