My son was tested at age 7 and again at age 12. His GAI showed a 35 point increase. He has some sensory issues and learning disabilities that had been addressed in the intervening years. Now, two years later, I'm guessing that if he were tested again, his GAI would probably be 10 points higher, as he is doing markedly better than he was the last time he was tested. (Of course, ceiling issues might prevent this.)