crowded skies? try flying on a GOOD day for gliding...
Invited to visit ATC at Upper Heyford, long ago, when Americans were running the place...they kindly demonstrated what their equipment could transmit.
It depended on the settings....they could actually see EVERY CAR AND TRUCK on the M40! And certainly any aircraft above 50 feet, whatever.
But the day that they dreaded was good gliding weather when gliding competitions were taking place. Talk about crowded skies? twenty or thirty returns in one thermal?
Power pilots, stay home, or practice your night flying!