did that walk several times last october - took me about 25 minutes from MGM to the International Gateway entrance (that's with a "shortcut" thru the Boardwalk pool area) - wasn't running, just walking and enjoying the view
My recollection is that most of this walk is out in the open sun with little shade. Not sure when you are going, but that could be a brutal walk in the summer heat.
We take this walk several times on every trip. You would think we would get enough walking in the parks, but this is a very relaxing walk. It can be very hot though in the summer, very little shade.