I believe the reference is to walking to and fro between White Cap and Castle Stone across the mountains. They can be scaled in a few places (without using Fly or even Jump spell), some with a struggle and others less so, also descended safely (if gingerly) without recourse to Feather Fall. An apparent graphical glitch could be a clue to the best route.

Having found two such "glitches", one each side, I'm convinced they must be deliberate. The "days off" are the 10 it would take going round by road, 5 south to Free Haven one side of the mountains then 5 back north again the other.

Oh, that makes a lot of sense. I always just flew, but did know that mountains in general are climbable. I was thinking of maybe a reference to the corners of a map, and going diagonally, but White Cap is special with the second town on the same map so what you said makes more sense with the gossip.