Tamping Mats are excellent tools to prevent damage within high volume environments. Not tamping without a mat can cause serious injuries within the wrists and arms. Tamp mats are also useful to ensure that bench tops do not get damaged while tamping into a portafilter.
When holing the portafilter against the tamping mats, push the portafilter in towards the counter away from you to ensure that the tamper remains fixed while tamping. A quality rubber tamp mat is highly recommended when tamping coffee.