When organizing baseball, it is suggested, in the iBook, Practice Baseball to Win, that the section of practice, called Individual, last about 20 minutes and include at least 2 different drills.  We’ve found with college players that concentration diminishes after 6-8 minutes.  With younger players you might want to do three different drills.  A little competition with this one will add some spice. For more about the book go to: practicebaseballtowin.com