From both the documentation and from my own experience, VRS doesn’t show you the absolute farthest range on the circles. I have planes showing up 25-30 NM farther out than what VRS records the maximum range at. There’s some reason they log it this way, the author explains it on his website.
Radio waves absolutely propagate differently in weather, day/night, bouncing off objects, etc. One day you’ll pick a plane up at 300 NM, the next day there’s no hope of that.
Some days I can pick up planes landing at the local international airport and show them on the ground, the next day I lose them at 200 feet up, but I’m only 25 NM away from the airport.
One day I can talk to France with a piece of 20 foot long coax in my backyard just strung in a tree, the next day it’s just static.
There are no guarantees when it comes to RF
VE6ADF (can you tell I’m a pilot and a ham? hee hee)