You don't need 5 shots to do HDR, nor do you need +/-3. On the weekend, someone had me hold their iPhone with HDR software loaded that used 2 photos for HDR. Personally, I find that very very few HDR photos look ok. Some folks like to do HDR with 1 "negative."
I'm really tempted to say from this quote that you're seeing people doing it wrong, but you assume their methodology is right.
There's many different purposes for HDR, let's keep in mind. One is to really blow colors out and exploit the tone mapping, another is to map more tones to a picture to mimic the natural wide dynamic range that you would perceive with your eyes (a lot of the "stunning" HDR photos out there you'd need to let your eyes adjust when viewing in real life - like looking at backlit mesas in a desert scene, with bright opaque clouds behind them).
I've tried pulling extra detail out of single exposures in Canon Digital Photo Pro for single-exposure HDR; it didn't work (for that instance...clouds became clipped). I'm sure that'd work for some cases. That is starting to sound like what I (poorly) understand Ansel Adams's zone method to have been partly about. I think that you can get perfectly acceptable "HDR" photos that look natural with just an extra exposure, if the software is good enough and the scene is right. One for more shadowy parts of the image, another for highlights. I suppose people like midtones too.
For five-shot bursts, I'd start to worry more about moving objects and camera movement. I have found that I've been able to do fairly well handholding even my T1i for three shot bursts with a heavy lens, but I wouldn't want to print the shadow tones too big (and thus the entire image's sharpness gets dragged down by that part of the image, though I suspect sharpness stands out more in highlights than shadows).