A dozen practices and hours of meetings have wrapped up for the Green Bay Packers as they finished up their organized team activities on Thursday.   The biggest piece of off-season training is now in the books as head coach Mike McCarthy installed all phases of his offensive and defensive systems.   The biggest benefit of the OTA's is for the new players, particularly rookies who now have at least a grasp of game plan basics, from the base offense to special situations like the third down and red zone packages.  The team doesn't get much of a break as the three day mandatory mini camp takes place next Monday through Wednesday.   Here are some final comments from McCarthy on the OTA's: