For years I used a 30/06 and Hornady 150gr BTSP. All were lung & heart shots on deer and they all went 30 to 70 yds.
The last 2 deer I shot with a .243 and Sierra 85gr HP bullets and they didn't go more than a step or two.These were both lung shots.
My belief, in this case, is the smaller bullets expend all of their energy inside the deer more efficiently.
To me, using more powerful guns gives you more penetration and more meat damage on deer, but doesn't necessarily kill any more efficiently.