This is intentional, but I agree something ought to be done. MediaLab requires an experiment (EXP) file, even when running a single questionnaire (QUE) file. So if you run a single questionnaire on its own, ML simply creates an EXP file for you that contains the single QUE file. However, I agree that aesthetics of the folder content were not given much consideration when we added this feature. I think it would have been appropriate to delete the EXP file after the session, treating it as a temporary file. Will add to the list of improvements for the next version.