The curlier a person's hair is, the less often she should use shampoo, unless she just likes having a Halloween wig on her head. Natural oil is in short supply for curlies, and what there is of it struggles to make it down the hair shaft.
Co-washing----washing with conditioner----is a common practice for curlies, including me. It cleans without stripping. I use shampoo once every 2 or 3 weeks.