In any case they certainly won't have anything like the kind of improvements people with ADHD has, improving from spectacularly bad to (usually) only slightly below normal.
It's a common mistake made by both professionals and laypeople that ADHD is a condition with only slight deficiencies in focus, when in reality they are often staggering.
Anecdotally, everyone with ADHD I've met understand the concept of things being so boring it becomes physically painful to do them. Everyone else think they heard me wrong.
For me the computerised test was almost impossible at the end, because my bored brain refused to even see the images on the screen. All I saw unless I blinked and tilted my head was a white, blank screen, only that it wasn't blank.
With methyl phenidate it was hard to understand it could have ever been hard, and that even though I still have significantly below average concentration even with medication.