Exploration using Maps.
Here is an example of using maps to explore. The map being used has been stepped twice from the original. I did not move from my first position of viewing the first map, the next stepped map, or this map, so that you see the radius of chunks rendered.
Mapping renders more terrain than I can see. Maps do top-down view rendering regardless of what is visible to the player. Extreme hills, ravines, forest are all shown. Using the mapping feature, I can 'see' 120 blocks in all horizontal directions. My render distance does not effect the mapping.
When you view my map walls, did you suppose that I went over each bit of terrain mapped? I did not. I only go around the mapping area once, and then across the center. The mapping feature renders everything that I need to see.
In Valour, since I can fly with a jetpack, mapping is extremely quick and easy. Supply world is much more demanding. Insania mapping is boss level. Good luck.