One fem can fill a 4 X 4 screen with a little guidance and 2 autos could probably do it too, 2 photos or 4 autos would easily do it, but it sounds like you are confusing or combining a SOG with an SCROG.

As Sub said if you decide to go with autos its a fucking seed per plant, with photo periods and you can grow as many plants as you want with that one seed.