I think we all tend to do the things you do, keeping a rough and ready kind of "where am I" calculation in our head most of the time. (For example, if I've got 4 miles from last water to next water, I know it should take me 2 - 3 hours to get there, and so an hour and a half later, I should be halfway there - which I can confirm with my map in general terms: "Yeah, I crossed that ridge about a half hour ago, after climbing some switchbacks, just like the map shows; it was just less than halfway, so I'm probably where I think I am.") Then we ration food, water, and remaining daylight accordingly.

Some of the folks we encounter, though, haven't got a clue. When they are going to "the waterfall" which you know is 4 miles in, and they ask "how far" when you can still see their car in the parking lot, all you can do is say, "A couple of hours, at least" and hope for the best. What's really scary is when the next questions are, "how far is it back to the parking lot?" and "can we hike back with you so we don't get lost?"