I have always mounted 2 blades or the main blades of 4 blades,horizontally.The theory was the broadhead has less chance to steer the arrow as it starts into paradox.
I don't know if it matters but I still do them that way as I'm used to that sight picture.OL Adcock suggests at least orienting them all the same and I believe he prefers horizontal.
I spent way to much time putting my arrows together,getting components to match in weight,tuned to the bow etc to have broadheads cocked in every direction.When I'm assembling broadheads and adaptors,it's a simple matter to orient them before spim testing.
I went a step farther and with an engraving tool,put a number on each broadhead and adjacent to it on the shaft,the same number.I have an aluminum external footing on the front of the carbon shaft and that makes a good place to put the number.
This way if I want to take several broadheads off and install judos,etc,it is a simple matter to get them back on the right arrow that the were oriented for and spin tested on.
I like the idea of getting the equipment consistent.Then if things aren't working right,I don't have to guess if it is the arrow,the bow,or me.It's me.
The "O" ring sounds like a great idea,especially for 3 blades.I would think it would help keep heads from unscrewing also.