In our phone application, when we have multi-step feeds, we usually ask one question per screen (except when it is obviously linked, that is, city and state).
Recently, people I have worked with have proposed placing several questions on the same screen because there would be fewer steps / screens to complete the task. I have always been of the opinion that, in one application, the single question motive "seems to me" faster, because I have the feeling of constantly progressing.
Has anybody done any studies on the subject? Basic rules?