Evidence aside, I really agree with Alice's statement on the building of relationships...

The time spent performing ultrasound (or another modality that allows relaxed conversation to take place) can have huge results for rapport building.

I think this rapport building may be more useful in some patients than others and we should ask ourselves:

does the patient have any underyling psychological issues (or even trouble opening up to you as the therapist) that would benefit from the extra time spent chatting? Or is your time better spent performing another therapy that may have more clinical evidence and proven physiological effect. Basically, at this point in time of treatment, what is best for your patient?