Hang on a sec here...
Now we all know I;m not even close to what normal people consider an expert. Not even sure I have officially hit "Nube" status honestly...
But I believe I recall someone at some point discussing shot placement. He used a video that displayed a deer dropping down about 4 inches straight down as the arrow came in. The idea was if you take into account that the deer tend to do that, then aiming lower would put the shaft right in the heart.
Am I off base here? If so... I need to change our practice shots all over again!