Not sure it’s the actual number of players - it basically doesn’t matter if you have 100 or 200 mutliplayer aircraft around you.
I noticed that the sim prefers players behind me more than the ones ahead of me since SU5, just like it was evaluating my position from some seconds back instead of my current position (which actually could be possible if the evaluation happens on the servers).
So when fyling in a larger group, most players I see are behind me, even if there seemingly are closer ones ahead of me.
But testing that is a bit complicated since it mainly happens if you have >30 (which is the limit I think) players so that the sim actually has to prioritize.
It’d be all easier, if the sim would at least expose multiplayer aircraft in a certain radius via SimConnect so you could see them in LittleNavMap etc.
Or if there was some website showing the WorldMap (which shows all players in your current view, not just the limited 30).