It’s comically easy to receive a diagnosis for ADHD and get a prescription for these medications, even in America. Many places don’t even test you, they just take your word for it and write you a script. Any athlete could claim they have ADHD (I’m surprised more don’t).
I too have taken ADHD meds. If you don’t take it for a test, you still gain massive benefits from taking it every day prior studying for the test, regardless of whether you actually have ADHD.
Is taking it on competition day the biggest issue? Of course. But taking it out of competition still provides benefits.