The rules I am designing can be played with two different levels. At the skirmish level, small bands of troops represent 1 man per figure. A “squad” might be about 10 men. It would still be very much a unit style game. Men rarely ran off on their own and operated independently. Never the less, when a figure is removed at this level, one man is a casualty.
At higher levels, 1 man represents a number of men. For my black powder era game, I would want battalions to be about 12-16 figures. If a small battalion were about 500 men then my rough scale would be 1 figure represents 40 men. Usually at this level, a cannon represents a number of guns. For example, at this level 1 gun would be a battery of perhaps 6-8 guns. Officers still represent 1 man plus a number of minor officers and men.