A paper, Patient Information-Seeking Behaviours When Communicating With Doctors, by Beisecker and Beisecker (Medical Care, Jan 1990, vol. 2, no. 1), has some interesting findings. The abstract is below. Although not recent, and there has been considerable change in the paternalistic nature of doctors, the findings relating to length of appointment may still be very relevant. Even if the actual time can not be given, patients behaviours may become information seeking if they feel that the doctor has time to see them. From experience, after 10 minutes, one feels that you are clinging on to stay with the doctor
Patients desired information about a wide-range of medical topics, but did not engage in many information-seeking behaviours when communicating with doctors. While desiring information, patients regarded doctors as the appropriate persons to make medical decisions. Regression analyses indicated that patient information seeking behaviours were more directly associated with situational variables (length of interaction, diagnosis, reason for visit) than with patient attitudes or sociodemographic characteristics. Patient attitudes influenced patient information behaviours only for patients with interactions lasting at least 19 minutes, indicating that a longer interaction may be necessary for patient attitudes regarding desire for information and participating in medical decisions to manifest themselves in information-seeking communication behaviour.
See the paper here.