Precision is a learned ability through practice and experience, and based on your description, you may have shot him in the "area of the shoulders" but maybe not precisely "through both shoulders" themselves.
Deer that are shot through both shoulders drop where they stand as their shoulders are now broken and they can't stand, walk, run, etc...even better, a precisely placed shoulder shot will usually take out the spine between the shoulders at the same time, dropping the deer in it's tracks stone dead.
But IMO, the heart shot is the best odds prize to go after...highest yield sure thing there is...not a shot in the "area of the heart" but a clean, solid heart shot.
Every perfect heart shot I've ever made with a round ball (.45/.50/.54) has dropped the deer within a leap of where it stood, or within sight of the stand after a 25-30 yard sprint...and they're dead on their feet after the first leap as I've watched them run headlong / crash into big trees at 30mph indicating they never saw it...couldn't compute, navigate, sidestep it, etc.
To your question, if I have a good broadside shot, I place the ball right behind the 'elbow' of the deers front leg...the heart lays low in the body cavity, like a large grapefruit layind down low almost on the sternum of the deer, a portion of which can be protected by the front legs depending on how perfect of a broadside shot you have.
If not a broadside shot, you have to 'imagine' the line the ball has to take to go through the middle of that large grapefruit...if he's quartering away, you need to slip the ball in just behind the last rib so it travels forward through the heart;
If he's quatering towards you, you need to slip the ball low into either the left or right front chest pocket, on into/through the heart.
:m2c: