How often should I be using purple shampoo?

I typically wash my hair every 4-5 days because it gets gross/greasy looking at that point.

I’m scared of ruining my freshly highlighted hair by using purple shampoo every wash since it is so drying. So do I use it every time? Or is there a different shampoo that I should be using?

I’ll attach photos of the products I use and my hair.