Granny may do what works best for her, but the insurance knows what they cover and do not cover. You have to understand what you are covered for. Insurance, when it includes both Medicare and Medicaid can get very complicated.
Once you understand what you are covered for, then you can go from there. Drs and nurses have a lot on their hands without having to understand everyone's insurance. That is why the insurance does a lot of 3-way calling. They have you and the Drs office on the call at the same time.