That counter is deeply flawed. It is more for counting all points in the polygon lines which make up the tracks.
Apart from that the FlightAware stats page only counts 1 position per 10 seconds per plane.
If you get more positions i don’t think you get credit.
Because yes you are correct the actual number of positions received (dump1090-fa has stats for that if you access pi/dump1090-fa/stats.json for example) then those are much higher.
For example i’m getting around 70 positions per second right now as i can see in my graphs.
That’s 70*3600 = 252 000 positions per hour.
But i only get around 15 000 positions per hour on the FA stats.
So maybe it’s every 15 seconds or something that you get credit for a plane position.