Kids need a balance of different kinds of activities. How will they get strong and develop coordination if they spend all their after school time and summer days doing test prep and/or extra academics? My kids did all their school work and homework, and they spent time reading on their own but no test prep. Went through GT/AAP, one is presently at TJ and another at a top 25 university.
No prep for GT or TJ. Too busy doing sports, arts, music, and community activities. Think their better off in the long run, and clearly it did not hurt them.