In short, the dispensing quantity depends on the pharmacist and the dispensing software they use.
At the end of the day, there isn’t a single correct answer for how much to dispense. Although electronic prescription software helps make things easier and faster, the pharmacist’s expertise and local regulations are still very important in deciding the final amount.
If you have trouble getting a prescription accepted at one pharmacy, don’t worry. It doesn’t mean your prescription is not valid. You might just need to visit another pharmacy, or consult with a doctor to request a bespoke prescription to adjust the format or quantities being prescribed.
More Information: Dispensing Quantities and the Realities of Electronic Prescriptions, Dispensing at the Pharmacy FAQs