The frequency of derma rolling depends on the needle size and the specific skin concern being treated. For smaller needle sizes (0.25mm to 0.5mm), it is generally safe to use the derma roller once or twice a week. For larger needle sizes (0.75mm to 1.5mm), it is recommended to wait at least 2-4 weeks between sessions. It is essential to give the skin enough time to heal and regenerate between treatments.