In many countries in the West, outpatient services are primarily provided through standalone doctors’ offices or group practices, or through outpatient services attached to tertiary care hospitals. Patients are seen by appointment in the outpatients’ clinic. The time of the appointment is based on whether a patient is new or has visited before, usually in the past one year, and is thus considered a follow up. New patients are assigned more time, usually 30 to 45 minutes; follow up patients are assigned 15 to 20 minutes. Most doctors’ offices divide the available clinic time into slots for new and follow up patients, and patients are scheduled into these slots according to availability. Doctors will usually accept some overbooking for urgent cases or walk-ins who come for acute exacerbation of a chronic problem.