at work we do build things to scale. We set our grid options as follows: Length and Width: 32 Grid Lines every: 16 Subdivisions: 16 Also give our Grid Lines and Numbers a black color. We leave the actual unit size at its default centimeters as that does not really matter. We treat each unit as a foot in this manner, so buildings will have 6' + tall openings so characters will fit through. I should mention that all studios will have their own way of doing things, but it's a good habit to get used to building things to some kind of scale.