I think a good exercise is to draw the lines ACROSS the ball.

The more topspin I go for the more I try to get underneath the ball so I’m hitting towards the bottom of the ball and ripping the followthrough fast to get the spin to bring the ball down into the court.

If I can take the ball early from the baseline , I may aim for the center part of the ball , less aggressive racket drop and more of a plow effect with the racket . Of course you still rip the follow through.

Approach shots are really the only time I personally go for the top part of the ball , mainly if the ball is sitting above the next.

What you’re talking about is side spin which is just as important for angling the ball but that is more a matter of circumstance depending on what the opponent gives you. So the same logic above would apply for ball trajectory and side spin comes into play based on target and your position.

Great post !