I used to have that same philosophy aiming for center mass with a bow. Just my opinion and for my particular issues on aiming. If your target shooting you have a dot or somekind of point of aim. I've shot too many times just at center mass and not quite hit as good as I thought I did. Take in consideration I don't normally hunt out of a tree stand so that's different.
I aim for the heart. My reason for doing so is I know I'm holding a perfect bead on the animal and not just trying to get it in there. Doing so the last 10 bow kills I've made have resulted in 3 heart hits and 7 just outside the heart. One was a bear out of a tree stand so I adjusted aim to hit the heart. It's vital for me to aim this way because I'm concentrating hard on my shot and form more than just putting up a quick lung shot. Nothing has went very far after being shot either compared to how I was shooting before. For me I have to aim at that one spot or it seems to go bad.