Generally speaking, in glamour photography we attempt to light the subject with soft light in order avoid distracting shadows and to render the skin smooth. This means the light source should be as close to the model as possible, and the modifier (softbox, umbrella, reflector, etc.) should be as big as is practical.
Smaller light sources further away from the model throw a harsh light on the model. There are instances, however, when this is desirable. Here is an example, with the model Andrelica:
Notice her shadow on the steps: clear and distinct - a sure sign of harsh light. Also notice how the light strongly illuminates the face of the steps, but the tops of the steps not so much. This gives an interesting graphic look to the image that soft light would not be able to achieve. The skin can be smoothed in post processing as needed. If the shadow on the side of the nose is not wanted, simply instruct the model to look in the direction of the light source.
There are other instances in glamour where harsh lighting is desired, of course. Using it to get an interesting, contrasty background is but one of these.