Citation needed. I'm sure are a few doctors out there who do that, but I have a hard time believing that's so widespread that it's a "habit" of "doctors." For instance, my doctor will reissue my long-term prescription if I call him, the next I hear of it is when the pharmacy sends me a notification saying it's ready.
That said, I'm sure there are prescriptions that actually do require regular long term medical monitoring by a professional, even if a lot of people are annoyed by that and therefore think it's unnecessary.