How far could the legions travel in a day

[Caius Fabius]

Romans matched their chariot teams by stride and height. They had litter bearers who were probably matched the same way. The idea of learning a Roman marching pace may be just that, everyone learning to walk all with a certain distance for their stride. If you look at some accounts, the soldiers selected for the legions were chosen by height, which would possibly mean the tent groups were divided by height as well.

I doubt that there is much about marching a modern drill manual could have taught ancient Roman, if they cared about it. They walked and marched every day, and had hundreds of years of experience and institutional memory. The modern military pace in the US Army is 30 inches, my normal paces is 36 inches, (we measure this for the sport of orienteering), but after being trained in the "Military Pace" I could "fall in to the pace" automatically, and with no problems on a short or long march, even when walking at the 'route step'.

We know from Josephus and Vegetius that they did march in a strung out column, with flankers and scouts posted to prevent ambushes. That didn't always work, but again, it is a TOTAL MODERN ASSUMPTION that Roman soldiers marched in "step". The ROMAN PACE is a distance, and has not been proved as a cadence. (And they didn't march to drums....)

If you give each man the individual distance that is mentioned by some of the ancient manuscripts, they were not marching in close order, and so would not have to worry about stepping on each other, as long as they kept their place. This is discussed elsewhere, and probably not worth repeating again and again. One either accepts what we are told by people who were closer to the time, or you add modern assumptions and 'know' something that is not yet proven as a fact.