ADHD doesn't have to be debilitating to be real. Many people have a legitimate diagnosis, don't use stimulants, and are able to cope in relationships and life in general, especially by the time they reach adulthood. That doesn't mean they don't have it. It just means they choose not to use stimulants to control it or they are high functioning enough that they can compensate without 24/7 meds. It's a spectrum. I had a classmate in med school who nearly failed MS 3 year due to untreated ADHD. It was so bad, the rest of us could see it a mile away. Truly scattered. Even his presentations and notes were all over the place. Somehow he got through MS1 and MS2 without meds (or so he said), but by MS3 there was no hiding it. Then you have people who complete med school and compensate without meds all the way through, but can't pull it off in residency. They may be fine when they're in clinic 9 - 5 with an attending keeping them on track, but when they're on a 24 hour shift by themselves, they may realize they can't get anything done because they're all over the place. And then you have those who are fine in med school during regular weeks because they compensate, but during exam week, when they're already stressed and have multiple things to study, their ADHD is out of control and they can't focus on one subject/lecture at a time. When they take the test, their concentration just isn't there and they're sunk the second someone gets up to use the bathroom or the second someone finishes the exam and turns it in.
I think prns are totally okay in the above scenario. In fact, I think we should be pushing for prns in general rather than daily dosing even when the patient doesn't need it. Why should someone who can compensate 90% of the time be forced to take the med and suffer the side effects every single day? There's really no justification for that, in my opinion, if they genuinely can get by without it.
As for prn doses being the same as abusing stimulants, I couldn't possibly disagree more. I'll offer this: would you feel that someone s/p car accident who takes opiates prn for pain (and finds that sometimes all he needs is Tylenol) is the same as the guy who buys opiates off the street without pain?