I usually have 2-3 different kinds of shampoo and conditioner in my bathroom. I found that if you switch once in a while, it makes your hair softer and bouncier! If I keep using the same shampoo everyday for a long time, my hair gets flat.
Listen to your hair. It can answer that question better than any of us can.
I am also a rotator. Every other shampoo, or whenever I have put more "products" than usual on my hair, I use Beyond the Zone Strip Search, a cheap clone of a Tigi product that has a lot of detergents and solvents, and is probably NOT a good choice for anyone with dry hair, or delicate color issues.
I usually switch when my hair doesn't like it did when I first got the product. For example, Dove shampoo/conditioner would detangle it right away when I first got it, but a couple months after it stopped. This is the signal to get a new brand!!
I rotate between Brilliant Brunette and Herbal Essences. I used to use just BB and my hair got dry, so I just assumed it was b/c my hair was just too damaged. One day I was at my parents house and had to use their HE and voila! silky and shiny hair. Then after a while my hair became the same way it was before ugh. So now I'm forced to rotate between BB and Vive Pro for damaged hair. I wonder what causes this need to switch shampoo & conditioner. Hair is supposed to be dead!
i wash my hair every 2-3 days and i switch between fekkai glossing shampoo/conditioner and fekkai luscious curls shampoo/conditioner. i have had good results and have been doing this for a few months now.
I use Herbal Essences one week and then Toni & Guy the next and it seems to be really working for me at the moment. I use the same conditioner everyday though, and once a week I use one of those great sink-in conditioners that you leave on for like 10 minutes, and I cannot recommend them enough, they make your hair soooooo silky.