I worked that out once…
hmm… I want to say that using the map 1" = 1 day
That would be hard travel in optimum conditions.
I’m sure there are examples in the comics that don’t synch with that figure, and I’m sure there are instances you could add or subtract time in adventures either with weather or terrain (driving rain or wind at your back, up and downhill on loose stone or downhill on firm soil)