That is pretty much what I do in country with hills and valleys. But, I have worked professionally in areas with large expanses of relatively flat forested ground, such as the boreal forests of Alaska and northern Canada. Useful landmarks can be rare in many of these places as are high points from which to view them. In these conditions, a map is less helpful than is a compass though I wouldn't leave the truck without both; the map will show where to find the roads. In fact, in these conditions, now, I would most likely use (ahem) a GPS.