When it comes to our skin-care routines, there’s no step perhaps more indulgent than doing a face mask. Whether you prefer a deep-cleansing clay mask or a hydrating overnight gel formula, there’s no better form of beauty T.L.C. than devoting 20 to 30 minutes to take care of your skin. “[Face masks] are designed to deliver high concentrations of active ingredients to your skin,” Joshua Zeichner, director of cosmetic and clinical research at Mount Sinai Hospital in New York City, tells Allure. “Generally speaking, masks are used intermittently to help give your skin a boost when it needs it.”