Given that some open plan employees sit shoulder-to-shoulder (as in, roughly 4 feet between chairs), yes, absolutely. I've also seen open offices with employees seated at 3-foot intervals around glorified dining room tables.

I’ve seen places where developers were nearly literally shoulder to shoulder and back to back. As in, the distance between people was determined by monitor width. With a normal sized keyboard, a 27inch monitor gives you about 6 inches of mouse space before you hit the next guy’s keyboard.

<shudder>