The best routes at every pace, and which controls were worth it. Once you've seen them, you can't unsee them.
You give your pace on the flat. The hills are added for you: each metre of climb counts as 10 m of running, so a 1 km leg with 20 m of climb counts as 1.2 km and takes 20% longer at the same pace.
With a GPX it works the other way round. Your elapsed time divided by that adjusted distance gives your grade-adjusted pace: the flat pace your run was worth. Distances follow the best line between controls, not your exact GPS line, so wandering or waiting at controls makes it slower.
Your run is split into a few grades, so one slow leg doesn't hide why. It's all worked out on your device, from your GPX and the map model: no AI, nothing uploaded.
Distances are grade-adjusted metres. Times use your running pace with the errors taken out: your elapsed time over the distance you really ran.
A+ is near perfect; E is a lot of time lost. Strategy compares points; Order compares distance with the best order of your controls; Navigation counts the metres your mistakes cost.
GPS is good to about 5–10 m (worse under trees and at night), so small wobbles are ignored. Route choice between controls isn't graded: on the ground you often know better than the map (gates, crossings, crowds), so the card only flags what your own line shows went wrong.