First: the what…
What is Strobing?
Strobing is highlighting, the opposite of contouring. It creates the dew-glow-radiance of healthy-looking skin. Like contouring, strobing can sculpt the face, too — but, instead of shadowing (which takes lots more time and skill), by making certain features brighter.
CONTOUR OR STROBE?
Contour when you want to achieve a perfectly sculpted look. Strobing is best when you have limited time or if your face shape already has a natural sculpt. Both at the same time work well as long as you highlight only one technique at a time.