After she rejects the physician's frequency proposal of “daily” as an estimate of her alcohol consumption, the patient finally comes up with an estimate of her own: "once a week." However she packages this as an estimate of how frequently she “goes out." This framing has two consequences. (i) It estimates her actual drinking in an implicit way, leaving it to the clinician to draw the relevant inference. (ii) It renews her insistence on the social, and morally acceptable, nature of her drinking, implicitly ruling out, for example, solo drinking at work, or at night after work.
With lines 15-16, physician and patient have arrived at a compromise: the physician has a frequency estimate of the patient's drinking, while the patient has been able to retain her focus on "how" she drinks. At line 17, the physician turns to the patient's chart and starts to write, subsequently acknowledging the patient's response with a sotto voce "okay" and terminating the sequence.