The neck at its bare basic is made up of 7 complicated bones that attach your head to the rest of your body. The neck bones serve as a portal for nerves and other structures that branch out to your upper body. Attached to the neck bones are many intricate large and small muscles that allow for both mobility and stability for your head, keeping it from falling to the floor.
I like to do these stretches when I am experiencing headaches. Sometimes, my neck muscles are so tight that they cause headaches and pain at the base of my neck. These stretches and exercises are also great to do on a daily basis. These muscles are commonly tight in most people. So my advice to you, do these exercises everyday, but especially if you're experiencing neck pain or headaches. Again, if you experience an unusual level of pain, go see your doctor!