Actually, the reason for my question about traffic can best be explained by "close calls" in times of heavy traffic not just on the ground when taxiing (near-collisions on the taxiways?) but also by take-offs and landing which are perhaps mixed up by ATC. After all, ATCs are only human and extreme pressure may perhaps lead to errors in air traffic coordination.
This is what also worried me, other than pilot/co-pilot being under pressure in heavy air-traffic... I really wonder sometimes whether it is just a matter of time before a serious accident occurs in one of those "mega" airports like Heathrow, JFK or perhaps Hong Kong due to ATC and/or pilot error in excessive traffic conditions?
I hope I'm wrong...
John