Because the Mojave is so big, and with a high enough perception, or ED-E as a companion, you can useually get some kind of blip on the radar when things are still a long ways out. In order to check on which enemies, freinds, or locations are closer, I use parallax.

By shifting left and right, and noticing how much the markers move with me, I can get a rough idea of far away they are. The more the dot on the radar moves the closer it is. So, does anyone else use this?

I use it too, but I call it common sense.

Never really thought about it but yes I do, just not an conscious tactic