When is it NOT okay to fill for the monthly ADHD prescriptions?

Patients are usually in their early to mid-twenties, comes to one single pharmacy for a count of 30 or 60 pills a month (they typically fill for generic Adderall, Vyvance, Focalin, etc.)... "regular customers" in the purest sense. The diagnosis is of course, ADHD. Most of these patients pay with insurance, a few pay with cash, and most are never early, so they always come and fill right on time. Should these prescriptions always be filled without ever questioning the doctors, since the... When is it NOT okay to fill for the monthly ADHD prescriptions?
Source: Student Doctor Network - Category: Universities & Medical Training Authors: Source Type: forums