Mike, and everybody, the problem with this sort of discussion is when someone says I am right and you are wrong.
Yes, science says that the optimum . .blah blah, but we rarely need the optimum and we are rarely able to actually test the optimum vs less optimum in real life because many other things factor in.
Many things, such as sharpness, angle of entry into the critter, angle of striking the bone in question, movement of the arrow ( paradox or other), movement of the critter, actual speed the arrow attained in the first place due to bow efficiency, actual draw length achieved, release etc. and more and more.
Dead critters tend to not jump the string very much, while our deer do. Water buffalo and others tend to be huge and every single inch of penetration might make a difference. Whitetail deer are not and I am gonna go on the fire here and guess far fewer deer are lost because of penetration issues compared to just plain screwing up the shot.
Enough penetration is very dependent upon what it is you are penetrating and changes constantly.
The speed at which an arrow spins is dependant upon where you measure and the rotation of the fletching, which changes for each of us with the flick of a screw on the fletching jig settings.
All that said. . . Ashby did a hell of a job recording his experiences and writing them down to share. I didn't do that, I am guessing most of you didn't do that.
Comparing penetration in critters against ANY kind of target substrate is plain bad science. Nothing out there simulates a critter like a critter. Not even close.
End result, do whatever you want. If it works, great, if it don't, I am sorry, and will help track if I can.
There is an age old body of experience out there to draw upon, using single and double bevel, right fletch, left fletch and no fletch.
Don't think you are inventing the wheel here, and please don't come on here and complain about the one you couldn't find.
Follow up and tracking is yet another skill set that needs to be learned and this might be a great place to learn more if the right folks share their knowledge.
CHuckC