Great tips , thank you . On slice serve if wrist is loose and used as a whip ( similar to table tennis serve ) the ball goes much lower above met but deeper. Why is it you not recommending fast swing? It is harder to get consistent serve though. For topspin serve don’t you want ball bounce on opponent side lower ? Then whipping paddle more sideways is preferred rather than low to high brushing?
original comment is correct, you can see the ball when it bounces on the other end of the court but not the travel from the stroke/hit off the paddle. I understand what is going on but visually unable to see the flight of the ball.