I’m not sure if this answers your question but this is what was explained to me when I worked in retail pharmacy.

Patient has opioid addiction from being on painkillers too long/too high a dose/abusing script. The patient has multiple doctors and specialists and requests painkillers from as many as they can get.

Doctors then become wise to the situation. Set the patient up on a “pain plan.” Now the patient can only fill opioid scripts from one doctor at one pharmacy.