The short answer is, "It depends." :) But typically once a week works best for most of our customers. It is not recommended for everyday use, however depending on the condition of your hair, it will not harm it. For those with healthy, hydrated hair, using it monthly should provide a good result. Average hair with minimal damage can benefit from using it weekly to every two weeks. Severely damaged hair (depending on texture and density) should use the product weekly/daily (daily use should consist of 7-10 days with a 3-5 day break in-between as to not over-condition the hair). If your hair is fine and/or prone to becoming oily, conditioning less often and avoiding the roots can be a smart adjustment. However, if your hair is thick and especially dry or damaged (from coloring, chlorine or sun exposure), deep conditioning more regularly can make a positive difference.