To my lay understanding, IQ is largely about potential and so assessment is more relevant early in the education journey. I am surprised that another IQ assessment may be applicable for end of high school exam provisions, especially if the student has already had more than one IQ assessment.

From your posts in other threads, I see that you are exploring a wide range of avenues to support your kids to develop their potential. I hope these achieve success and obviate the need for further IQ assessments.