Combined products are practical and saves space in both your bag and your bathroom. With a Hair & Body Wash, you get a good shampoo to wash your hair clean, but you can also use it to clean your entire body. You do not need to bother with multiple bottles or tubes. Many Hair & Body Shampoos are 2-in-1 products but there are also 3-in-1, where you also get the moisturizing properties from a conditioner.
Many brands have both body wash, deodorant and perfume in the same series. If you use these together you will smell more uniformly and top up with your perfume.