Othismos true nature

[Paullus Scipio]

There is a tendency to converge laterally when you run. Watch any group of athletes run a sprint- you need lanes on the ground just to keep them apart. (Don't watch a race that goes around a turn for they converge to minimize distance, so its not the same effect). This is common to all animal herds or flocks and takes discipline and training to overcome. Those of you in the military probably know that "bunching" is always a bigger problem in spacing than "spreading".

Very true, and I suspect you are going to argue that this is what happened in Hoplite warfare, which it undoubtedly did at times, but as you also say, much military training is put into overcoming the trend, then as well as now.