how long?

everyone who plays tennis
will tell you that the secret to an ideal shot
is to keep the racket on the ball for as long as possible.
many pull up too soon.
many don't give enough time for the ideal hit,
no matter how much they want to play perfectly.
but then again,
you can only keep the racket on the ball for so long.
after that,
there wouldn't be any point to hold it out there,
once the ball has left the racket,
flying towards your opponent.
so instead of looking like a doofus with your hand stretched out,
you pull up,
finishing the stroke.