People are undoubtedly some of the most interesting subjects to shoot and some of the most interactive.
While tethered to your computer, an art director or client may be on the set observing your process. Being able to share your images as they are created has an enormous impact on client/photographer communication and provides great opportunities for feedback and shot discussion.
During intermittent breaks, the subject model may become curious and want to see some of the images as well. It is usually best to keep the model focused on their role in front of the lens as sharing images mid-shoot will not only take valuable time, but your subject may get self-conscious about a blemish or become unhappy with something they see in the images. Keep them focused on the current task at hand.
Once the photo shoot has wrapped, let the model review the images if they wish.