It is possible that at the beginning you practice only two or three days a week but Ashtanga Yoga is a method designed to be practiced 6 days per week. We must also rest on full and new moon days. This is the only way of practicing Ashtanga correctly. If you practice just two or three days a week, it will be a superficial practice and you will never understand or reach the physical, mental, emotional and spiritual benefits that this practice provides us.