From the National Federation of State High School Associations (NFHS) Baseball Case Book used by umpires:
6.1.2 Situation A: With no runners on base, F1 (Pitcher) starts his windup or preliminary motion and the ball slips from his hand. RULING:There is no infraction provided F1 delivers a pitch within 20 seconds after receiving the ball. If F1 fails to do so, the batter is awarded a ball. If there had been a runner or runners on base, dropping the ball while in contact with the pitcher's plate is a balk if the ball did not cross the foul line. Each base runner is awarded one base.
Comment: 20 seconds is an eternity when delivering a pitch. When is the last time you saw a ball awarded to a batter for the pitcher not pitching within 20 seconds? So the answer to the question at the start of this thread is NO ball should be given to the batter.