you do what you do and i will do what i do.! since i help on a beef cattle farm and grew up on that farm all my life, we slice the jugular not to kill it faster but to use the heart as a pup to get the blood out because it taints the meat. so you do what you do hoss!Neck, neck, neck, NECK for crying out loud. They don't die any quicker with a heart stab, and could actually take longer specifically because it's difficult to hit. If this is while hunting, you definitely want the heart to pump out as much blood as possible.
There's a reason when you slaughter an animal you cut their jugular and not slash their heart. Also, don't twist, thrust in to the hilt, then pivot the blade along the skin making for a nice smooth cut.