> I have no idea why you'd want to be taking a test a second longer than you already have to.

The theory was that ADHD students have trouble sustaining concentration, so extra time allows for thought breaks and distractions. The idea was that 2 hours for the ADHD student would be similar to 1 hour of concentration for a non-ADHD student, and therefore the inequity had been partially compensated.

The teachers I know have the same observation that you do: The extra test time isn’t usually used by the ADHD students, but when other students (or maybe more accurately, parents) discover that extra test time was available, most of the high performing students suddenly got diagnosed with ADHD at the same time. They were the ones staying extra long to proofread their work.

For the elementary/junior high teachers I know the schools’ solution was to give everyone the same extended test taking time. Easiest way to remove the incentive to seek out a fake diagnosis without taking anything away from anyone.