Looking at the manufacturer's diagram of a racquet SS, it's all over the place. I think a manufacturer's SS is way over stated. A player's SS is much smaller. And it shrinks with greater playing level.
For me, hitting strokes above the horizontal axis is not sweet. Hitting strokes below dead center is not ideal. I like the hitting the ball toward the top (of the racquet), slightly below the horizontal.
Up your backhand.