We hear this question a lot- "How often should I shampoo?" The funny thing is, when we tell people the answer, they are SHOCKED! All we can say is, don't believe everything you read in Cosmo.
The amount of greasy heads walking around is actually shocking. Not only does it not look good, but it is NOT good for your hair or scalp. The scalp needs to breathe in order for the hair follicles to receive oxygen. Can you imagine if you didn't get oxygen? Why would you deprive your hair of it?
The magic answer to how often you should shampoo your hair is however often it takes for your hair to get the SLIGHTEST bit greasy. Sometimes, this means literally twice a month, and sometimes this means every day. It all depends on your hair, and everyone's hair is different. If your hair develops buildup everyday, it is 100% okay to shampoo 365 days a year!
Unless you're a twin, your DNA is different than anybody else's. That means, you should treat your hair differently than your friend treats his/her hair. Shampoo when your hair is the slightest bit greasy, and you'll be doing well for your hair!