I don't know how anyone can shoot a stickbow vertical. I can't do it. The bow blocks my dominant eye.
I cant somewhere between 30-45 degrees depending on target distance. Long shots are more vertical, short shots have more cant. It's not something I think about, just happens naturally.
I shot a big groundhog the other day at 12 feet with my Abbott longbow. I certainly didn't think about form when I quickly drilled it right in the chest.
Shoot the way that feels comfortable to YOU, doesn't matter what we think.