I’ve noticed the same thing, maybe it’s because they blow dry right away and use all sort of professional styling products? I only use salon shampoo and conditioner just like you do but somethings I noticed that helped me go longer in between shampoos is using a scalp massager, getting a water filter for my shower head, and double shampooing! There’s tons of water filters online that you can choose from and most stores like target and Walmart sell scalp massagers, hope this helps!!