For documentary style interviews I use low-wattage energy efficient photographic bulbs e.g. 115 watt consumption but 625W equivalent output. I use 2 per light stand through a white umbrella - gives great soft diffuse lighting just out of shot (2 or 3 feet away from where interviewees are seated). I usually place I light stand at either side of the person (typically one at 90-degrees and the other at 30-degrees). But when you're in a large conference room in a hotel which is what I use (hire them by the day) you still need more light. This is where the Red-Heads are really useful. Yes they give out tremendous heat if you're 6 to 8 feet away from them, but not so at 25 - 30 feet. Then you can light up backgrounds (so no shadows from main umbrella lights). You can point one of them straight up at the ceiling (if painted white), plus you can bounce them off walls, glass shelves, bookcases etc.
Red-Heads are the cheapest way to light a hall/room/theater and so on, plus they get the job done on a budget. Yes they are power-hungry, hot, and dangerous to touch when switched on, but for a couple of hundred bucks, they're great. And you can use them outside, in the garden, with an extension lead, they're not heavy (you can pick up with one hand and move very quickly). Finally the barn doors allow you to direct light away from camera tripod, or away from faces of people, basically to where you need it. Plus the bulbs may be moved forwards/backwards within the heads so allow for either a wide-angle effect or a more directed spotlight one.