Setting a ground and time scale for a game allows one to calculate movement rates, and furthermore provide a frame work for the number of actions that can take place within a turn; whether it represents one minute, or one hour, or one day. However, one problem that emerges from this basic process is that table top wargames almost always end up with a discrepancy between the figure scale, the ground scale, and the time taken to play a turn versus the time the turn represents. This comes from the desire to have games that are not just small skirmishes, or gladiatorial fights, but rather play out large-scale clashes between armies.

In BattleTech for instance, the rules state that each hex is 30 meters across, and serendipitously each hex on the map board is approximately 32mm across the flat sides, which means that the ground scale approximates to 1/1000 scale ratio. If the models were to the scale of the map boards then a man would be around 1.8mm high, and a mech would be about 12mm tall.

For comparison, in OGRE/GEV the hexes are stated as being 1500 meters, or 4950 feet across. Now let me see that would make the scale of the vehicles, very, very tiny indeed. Quite clearly the models are being used as counters in this game, as they are much larger than the ground scale. Whereas in BattleTech the use of models makes it feels very much more like a miniature wargame.

Even so, we still see that the models in BattleTech are are three times larger than the ground scale. However, this is not unusual thing to see in table-top wargaming, as using a smaller ground scale allows the game to represent a larger area on a table. The traditional wargaming table is often six foot by four foot (1.8 x 1.2 meters), and the use of a smaller ground scale to figure scale often goes hand in hand with another concept of having a model represent a multiple of itself.

Still, one can see that there are quite a few problems that stem from any decision that changes the ground to figure scale.

When game rule really start to break down is when trying to represent fighting in cities with large numbers of units. This results from the disparity between figure and ground scale that  breaks the verisimilitude of the game.

Let's look at why this happens? Take for example figures at one three hundredth scale that are approximately six millimeters high, representing a man six foot tall. If you then play a game on our hypothetical standard six foot by four foot table, then you get an area of approximately eighteen hundred feet by  twelve hundred feet in size. Sounds enormous. It isn't, not when you think for a moment about how fast a vehicle that can move through it in under thirty seconds when travelling at a modest thirty miles per hour.

This is why the ground scale is usually smaller than the figure scale.

It's a typical catch twenty-two situation where the solution leads you back to the problem. Never more true when trying to fight in a built up area, as ground-scale comes and bites you on the leg like a demented pit-bull terrier.

One answer is to keep the disparity between the figure and ground scale to a minimum by using smallest figure scale possible, because this will keep the ground scale reasonable for the area you wish to fight over. The other answer is to write the rules so that the problem disappears as an abstraction. Neither answer is right, and neither is wrong, but when you have rules that try to account for everything, you end up slowing down the game, and that is a problem.