I regularly try speed painting, with tuto and video and all. And it usually end with me crying under my desk in despair (ok, not literally), with the picture deleted or rearranged to look like something ok and more classic. But I don't give up.
I don't care much for speed painting. I don't have the skill to make a consistent picture in thirty minutes. Heck, it takes me thirty minutes just to make the lineart for a picture, let alone trying to color one. xP