I believe without a map, it would take much, much longer. As mentioned previously, you would hit a lot dead ends. I could not handle following a road going in the right direction and after 20 miles it ends in the middle of nowhere.
And yes, the early world explorers faced just that, for this reason they would be gone for years and many never came back
I was into orienteering when I was young, but in the bush, where I had to go from point A to B without trails or signage.