One-on-one:
Used mostly to find insight, opinions or recounts of events.
Group:
Used to create a more open, discursive atmosphere.
Location:
Used to establish the talent’s situation, setting and actions while creating a natural soundscape of their location – gives an all-encompassing authentic feel, often speaking of the present.
Studio:
Used for a controlled, targeted sound, drawing focus to intonation, inflection and raw content. Usually produces higher quality aesthetics and can provide more insightful content.