Is it important to walk dogs in different areas each day?

I walk my chihuahua mix (14 mos) twice a day. We walk a half mile to take the kids to school and then a half mile back, and then again to pick them up. I thought 2 miles a day should be plenty for my chi. But, I was reading how dogs have to go on walks to "explore" and get that natural instinct of exploring out of their system and thats why you shouldnt just let them run around a yard, etc. But, she isnt exploring much if she goes the same route each and every day.