When I tried Hawes to Grassington, it came up with the obvious road route over Fleet Moss, and the minor road between Kettlewell and Grassington.
It will suggest poor routes though - for Aviemore to Braemar, it takes you through the Lairig Ghru, which is positively dangerous if you don't know what you are doing.
Interestingly, it also leaves the Aviemore-Glenmore road via a fairly major ford and little used track a mile or so after Coylumbridge, rather than taking the obvious well surfaced track from Coylumbridge via the Cairngorm Club footbridge.
It would be an improvement if the Geograph photos could be sorted to show those closest to the click point first. On the Lairig Ghru route, the Piccadilly signpost appears first even if you click down by Corrour bothy, 8.25 miles away. Many of the more recent photos have quite good locations attached, so it should be possible to put them in some reasonable order.