once every 2 weeks is not as bad as most people do it. But rubbing your roots will break some hairs, and the hairs by your roots are the most important for the integrity of your locks. Doing it often will create sores and scabs under your locks, but only once in a while wont do this. But you will be ripping out a few hairs here and there. And in 2 weeks, those hairs will not magically grow back into your scalp. In fact, the new growth that will help fix that damage is 6 months to a year away from being long enough to fix it. And by that time, the spot where the damage is done is now 6 inches further down your lock. So you will constantly be 6 months behind the healing length. So it's best not to mess with your roots at all