With the last couple of flights I've flown , it seemed to track them very accurately . We were conducting practice approaches and I was surprised it reported alts for each stage of the approach accurately including minima.
A friend tracked my last flight , we worked out it was very close to realtime.
Baswell we were IFR however I think it tracks based on discreet squawk code as I've notice a number of flights cruising at VFR levels.