It's not really a "problem" because you can usually get them the same day, but I can assure you that it's a thing, especially if you take controlled medications like Methylphenidate.

An even more fun quirk is that because different pharmacies seem to use different distributors, you'll sometimes have to hop around until you find one whose distributor has whatever your medication is in stock. I once had to go to four different pharmacies in Mitte before I found one that could order Zolpidem.