THX Solvent for this answer...
On the real battle, the battalion length in formation of line was around 130 meters... 600 men per battalion, 3 lines, 0.65 meters shoulder to shoulder, so the length is around 130 meters; it's the length in the game.
In fact, the 3D model width is around 1.5 meters, high around 4 meters; moreover all objects (trees, building) use this scale factor so all seems right.
Gap? just if the length of the deployment line is too important, you have a gap between the units.
The paintings of this epoch show a huge density of troops.. but I am no sure it's a precise presentation of reality, just a nice painting.
JMM