puffin and Minichi - this old post describes a bit of what you mentioned.

On the other hand, 85% sounds like a reasonable level to score. Given that information, the testing requirements may be to protect your child and the school: Having a process/procedure with a paper trail of documentation may help ensure that a child is likely to achieve success with his/her single subject acceleration. This could keep an child from being "pushed" ahead when s/he is not ready.