You can practice these exercises parallel or turned out depending on what your body needs. Parallel will concentrate on the hip abductors (outside of hip) where rotating the leg will work on the external rotators including the gluts. Additionally, I find with parallel work more of a hip stabilizing emphasis, and rotation students feel more of the hip length and stretch (flexibility). A ballet dancer I work in parallel to balance out their turn out. With a student that rolls their knees in, we work turned out. Doing both isn't a bad idea though.