I am a fixed crawl shooter, so I need the point of my arrow easily viewable and the spot to hit, so I mount my Sharks and Deltas horizontal.
Vertical, when at anchor I have middle finger against a tooth in the corner of mouth, feather touching nose, thumb knuckle under jaw and back of broadhead blade just touching my index finger on my bow hand. If any of those is missing then something is off.
I mount them so the arrow spins true no matter which way they are.