Sorry no idea. I suppose i ahd to lie if i would name an exact number. I suppose my Alien Scene series were the most greatest scene i did with a basic and advanced knowledge. It has got with all the aliens in it, the huge station in every detail, around 4,2 million Polygons. This was very annoying workind on it and also rendering this in HD Quality (it isnt finished and i am not working there anymore.. hahaha what a noobish task)
Earlier I worked ion huge lowpoly scenes as a beginner with very high polycount, I remember a small city with around 800k polygons..