"Do you aim low on deer"?
All depends on where I am and the body language of the deer.
Here in GA I hardly ever aim 'low' on calm deer....and aim for what I perceive to be the lower 1/3rd of the lugs as deer may or may not move, and most times they will move a tad as most end up shot middle of the lungs a couple of inches higher. It all happens so fast its really hard to see the initial movement. If the deer is alert, and still close enough for a shot if I decide to take it, then I aim for the white hair line (heart or base of the lungs depending on the angle).
In TX, I ALWAYS aim low....baseline of the animal to be exact. Listen to Wingnut, he and other TXens know of what they speak. Those TX Deer WILL show you movement before your arrow gets there as they are always on alert it seems whether their body language shows it or not. You can plainly see your arrow zeroing in on the exact spot you wanted to hit and they will duck the arrow in the last split second before your very eyes.
It was hard for me to aim low even though I was told to when I 1st started hunting TX, but after the 2nd big buck ducking on 'calm' shots two years in a row I finally gave in and started shooting all bucks and does in TX as if they were on alert.
Below is a typical scenario.....
A TX doe shot from 15 feet up, and 15 yards out broadside. The yellow line is where I actually aimed(yes, baseline of the deer), the impact point was the entry point, and the blue line is the EXIT hole on the other side. YES, the exit hole was actually HIGHER than the entrance as the doe not only ducked but laid over to that extreme. Again, Wingnut has told me he's had this exact same thing happen.
I'm not telling anyone 'where to aim'....just telling you 'where I aim', and you can make the call for yourself based on your observations at the time.
I also don't believe smaller feathers will help either in TX. I truly believe you could shoot an arrow with NO feathers and the deer will not be in the same spot when the arrow arrives.