Normally, if you ask me “what is the studio portrait setting”, I would say 1/125th sec, f/8, 200 ISO.But sometimes, even when you are essentially shooting “studio-type” photos, you can use narrow depth of field.

Like in this picture, where the only thing that is in the plane of focus (i.e. that is sharp) is the face:

This was an 85mm lens set to f/1.4. The light was a bounced (behind me) flash. The f/1.4 gives us a depth of field just enough to have the face, and only the face, sharp.

So when you do a portrait, ask “what type of portrait”. You will not often want to go as wide as f/1.4, but the question is always the same. Whether you are in a studio, or shooting studio-type flash pictures in any environment.