Deer heads aere always moving, down to graze, up to scan for danger. Which makes them a hard target. Unless you are jacklighting them, have their eyes locked on your light.
It results in a low consistency shot. If the deer is grazing all 4 fleet are planted. The body is not moving, or at most is moving forward at a slow walk.
The heart is right behind the elbow. 2 inches right of the elbow, that is your aim point. If the adrenaline is up I have seen double lung shot deer run a mile.
And the best thing you can do with any chest shot deer is after that shot sit down and give it a solid 15 minutes. It will be listening for pursuit. If it hears not it will stop at the first place that has cover and it will try to patch/clot that exit hole. A little pile of dried leaves or grass and it will lay down with the injured part on those leaves. 15 minutes is enough time for it to cool down, stiffen up, and bleed out. Walk up on it quiet chances are it will be laying there dead or almost dead. Easy to finish without another run and wild shots.
Bow hunters know. Shoot a deer, hit it in the right spot, give it some time to bleed out and stiffen up. Makes the follow up easy.