Buildings - how close?

[PhilM]

I am building a very narrow switching plank with industries place along both sides. Along the back they are little more than flats - maybe 1/2 inch depth. I want to create the impression of and industrial canyon in a fairly modern business park (perhaps buildings no older than the 1960s maybe a bit newer) in a medium size midwestern city. Anyway my question is how close to each other can buildings be and still look prototypical? The closer they are on the model the less I have to worry about the gaps and merging the buildings into the background.

thanks
Phil