Co-washing is not just for curly hair. If you check out the Long Hair Community there's an entire thread for co-washing and there are just as many posters with straight hair as there are with wavy or curly hair. Texture makes more of a difference than curl pattern- people with fine hair (wavy or curly) sometimes cannot co-wash exclusively and may need to rotate in a low-poo. But there are definitely wavies who do co-wash. Ultimately, the key to best enhancing your waves is to find the right balance between moisture and protein, and this can take time (that balance can also shift with changes in weather, etc).
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