Hoplite spacing and formation

[PMBardunias]

...Fair enough, but my understanding was that your 'model' of 'Othismos' required the tightest possible formations both laterally and depth-wise,

The model only requires tightness in depth, but I do believe that they overlapped shields. The only way this can occur consistant with the model in right over left (you have confused r-l and l-r in your description of "natural", which is l-r)

....even a gap of a few metres is fatal to the whole 'phalanx/shieldwall' concept of fighting.
Let us do the exercise with a minimal overlap, say 6". The gaps between Lochoi then become 17.5 yards(16 metres)...11 of them, each one more than wide enough to be fatal to your phalanx..

You forget that lateral drift of the entire line occurred as well, and was probably asymetrical along the front, though not the 50 yard dash you ascribed to the men on the left. The combined effect would perhaps reduce this to 15'- 30' gaps. Hoplites could not effectively exploit gaps such as this without breaking their own battle-line and exposing their unshielded flanks. This is the weakness of such linear tactics. Xenophon tells of this a bit of this effect on light troops when he describes that odd formation of a battle line of spaced Lochoi, Orthioi lochoi.

...since the whole point of 'Othismos' was to create such gaps, your argument is self-evidently mistaken.....anyone can give numerous examples of gaps leading to defeats.

The point was not to create a gap, but to beat back a section of the line causing a buckling effect. This is a matter of scale, but bending your battle line into your foes and pushing him back is different than fragmenting your battle line to exploit a gap. I seriously doubt that hoplites had the tactical flexibility to exploit a gap that would require breaking their units front line into fragments to fit in it- ending with them being flanked on both sides!