I mean, even that is kind of about treading known ground. Unless it is fairly straight going on very flat terrain, you are going to find your estimates fall apart REAL fast (… unless you are doing a forced military march where people are getting berated/whipped if their strides are too short or not with the rhythm of the cadence). Let alone any winding trails.

Its why, historically, one of the most valuable assets is a local who knows the terrain. Whether that is letting an army know about a really good place for an ambush or just helping to navigate even a bunch of fields in a valley, let alone mountainous terrain.