The packaging says that the shampoo should be used as a once-a-week treatment, but it’s all up to personal preference. I usually only use a clarifying shampoo when my hair starts to show signs of build up and residue. I’ve tried to use the Neutrogena Anti-Residue shampoo consistently as my regular shampoo because I only wash my hair once or twice a week anyway, but it was too much and it dried out my scalp. How often you use it will really come down to how much product you use in your hair, how often you heat style it, and the quality of shampoo and conditioner you use.
I recommend using a tried and true shampoo for your hair type regularly and rotating the Neutrogena Anti-Residue Shampoo once a month or once every other month depending on your needs.