@aeva I had a pharmacist (in California) that filled on day 27/30, though at some point I had to switch and my current one only does 29/30. Still rough but not "literally zero margin" rough.
More than one pharmacist has claimed to me that their refill policy was law, when in reality it was some combination of insurance policy, corporate policy, and their own ego (they have some discretion and this is one of few places where they actually get to use it). Walgreens was the worst about that.