There's no one right way, even though some like to make everything into a mine's-better-than-yours-I'm-smarter-than-you pissing match.
And I'm not one of them, there's room for everybody's pet theories and toys in this game.
Those numbers came from the online JBM program, at 0 degrees and 0 sea level. Our altitudes and ambient temps are very different; except for one sheep I don't think I have ever hunted at 80 degrees.