Hi!
The area where you hit your head as such does not affect the time to heal. It is more dependent of the force of injury and the level of brain involved. However yes, the base of the skull is most sensitive and a hit in this area can cause more trauma than in other areas. Also a direct impact on the top of the head can be really injurious.
Healing from concussion is a very unpredictable. A small injury may take time to heal where as a bigger injury may heal faster. Take care!