There is indeed a walkway from Sat. 3 to 2F. When you get to the center section of 2F (where the escalators to the train arrive), instead of going down to the train that would take you to 2E, look for a small escalator going up. That will take you to a longish walkway to 2F. I have done this transit a few times and do think it is faster than going back to 2E and using the tunnel over to 2F.