watungga
Professional
To me, too many player's are stuck at backscratch, and can only get 3/4 power without learning the full loop swing, which is a 360 degree serve swing, starting from trophy with the racket pointed AT the sky above your head...or slightly forwards of vertical.
Those are just guidelines to advance personal serving technique. Can't push someone to strictly follow them completely. By my experience, it would result to a larger disappointment when situation gets tough.
To each his own.
I have a way to push them toward the 360 serve swing as long as the trainee is capable of power hitting with loose grip and a consistent toss.