Depends on the skin type and specific skin problems. For oily and mixed skin, using SQT Resurfacing Repair Set to treat pimples, acne, diminish acne marks, improve acne skin, etc. requires 1-2 courses of treatment, A course consists of four treatments with a 2-week interval between treatments; using SQT Revitalizing Beauty Set to improve skin texture, even skin tone, delicate skin, and lighten melanin requires 2 to 3 courses of treatment, 2 weeks between treatments.  For dry and sensitive skin, it takes 2~3 treatment courses to use the Rejuvenating Beauty Kit to adjust skin texture,even skin tone, delicate skin, and lighten melanin,2 treatments the interval is 3-4 weeks.