3 mph is reasonable walking pace, 4 mph is probably closer to a forced march - at these speeds it's probably more likely to be a matter of perspective.
Expected distance at outset is probably more important when determining overall pace - 'leisurely' would have to factor in 'breaks' of up to ten minutes per mile etc for example.
I like to think of Harold's march from the South Coast of England to just a bit North of York as our benchmark of what actually happened, when thinking of what is reasonably possible. From London to York was ~200 miles, and carrying a lot of weight by way of wargear, he managed to cover at least 20 to at most 30 miles per day, every day for what would have been just ten days. Bearing in mind he was probably at the head of a fighting force of up to ten thousand men, they probably stretched back for some ten miles of road at a time. It was a feat of arms that would have been the stuff of legend had it not been subsequently superseded.
Imagine watching this army march on and past your village, probably taking a few of your men with it, crunching, jangling, and shaking the ground as it wound its way onwards, like nothing you'd ever like have seen before, taking the most of, if not more than, an hour to march past your house.
People walk at 3mph, that's a reasonable assumption.