Definitely preference. I am normally on wide open as most mentioned above. And I take lung hits. The fiancé likes the two, and sometimes one, hole setting cuz she takes mouth to lung hits. Feel it out. You'll know soon enuff what worx for you. The ST is great and is my ADV to, from and at work. Even between rdas while at home. I always try to keep it filled with my fav juice mix. Love rebuilding the coils on it too!