All spaces are different, but for most applications you would need about one light every 12 feet, and the average tent or ballroom has 180 linear feet of perimeter, so we would ordinarily use about 16 fixtures. However, when you subtract for doorways, fireplaces, or other nooks around the perimeter, 12 or fewer fixtures could easily suffice.  For larger venues, multi-room, specialty applications (Statues, Fountains, Walkways, Pillars, Cake Tables, etc) more may be needed.