Very Large Spaces
Can a gymnasium be lit with a 3-light setup? Probably not.
There is a limit to the size of an area that can be lit with portable lighting instruments. Those people who use flash cameras to light up Grand Canyon at night--their flash isn't going to illuminate more than about 15 feet. Even in a stadium, a flash is useless; as are all but the most powerful professional television lights.
In a large room (say, a classroom) one approach is to try bouncing a light or two off the ceiling. The advantage is that it brings up the general light levels of the room--and the bounce produces appealing soft light.
The good news is that most modern cameras can adjust for the color of whatever lights exist in a venue (called the "house" lights). So if all the lights are on, it should be possible to get a reasonable wide shot. But when going in for closer shots, the house lights will likely produce unflattering light. That's the situation where setting up a 3 light setup would be beneficial.
