So, obviously, just don’t do large instances at all, right? But then we’re back to the discoverability, administrative, and operational problems. (All of which can be pitched as features, if you look at them from the right angle).
Basic models of flocking behavior are controlled by three simple rules: 1) separation: avoid crowding neighbours (short range repulsion); 2) alignment: steer towards average heading of neighbors; 3) cohesion: steer towards average position of neighbors (long range attraction). With these three simple rules, the flock moves in an extremely realistic way.