The vast majority of european kingdoms were more than a day's marsh in radius. The handful of exceptions doesn't make the rule.
As for the "not in large realms", which I suppose you mean kingdoms, I don't see why not. Regardless of how large their lands were, allies would, when marching, not be that far apart. The distance between their homes has no relation with the distance between their tents.
Not until the later periods did they march together, and even then not as a massive block. Logistics require that large armies move separated in most cases, and before that parts of the army would basically take whatever path they wished to reach the designated marshalling point, often taking detours in order to secure a food supply for themselves or loot some tasty target. This was long one of the biggest hurdles for armies, first you had to know which of your nobles was actually going to honour their commitments and march, then you had to hope everyone that intended to fight actually got to the location in time.
