I work as a nurse in a primary care office and our appointments are scheduled for 10 minutes as default. 20 minutes are used for new patient meet and greets or acute visits that require more exam and tests such as SOB, etc. My office completes the stress tests, EKGs, labs, and vaccines all at the time of the visit once the provider orders them so it is helpful to have a little more time to complete these orders. The appointments are generally back to back and a provider can see on really busy days about 30-40 patients depending on if there are also physical exams scheduled (40 minutes). Depending on the mix of patient appointment complaints/types determines how many patients you will encounter.