Each hex represents...? Each soldier is...?

But in a scenario you can make it what you want. I did a large map of Green Beach (Dieppe Raid) with two inch hexes representing 100m and it was 4 foot by 5 foot in size to get that one part of the battlefield in.

I usually also bend time as well. I have had AAM scenarios where each turn was a minute of the real battle, an hour of the battle and even where the turns represented a day of the 7 day battle.

Don't be constrained

The hexes are 100 yards approx. This applies to both 2 & 3 inch hexes, the larger hexes came with the vehicle scale change.

Both scales are "accurate". The two-inch hexes represented 100 metres (not yards). But when the vehicles were upscaled from 12mm to 15mm (the so-called Version 2 vehicles), the maps were issued in three-inch hexes, again representing 100 metres, so the new, larger units would fit alright.