So does this work for all hair types, or is it more for certain textures? I've heard mixed things, and it makes me wonder if the water temperature needs to be ice cold or just cool. Your test on dry ends is interesting, but what about the scalp? Does the cold rinse affect oil production or anything like that? It's funny how these old tips sometimes turn out to be true after all. But really, how long do you need to rinse for it to make a difference? A few seconds or a full minute? Just trying to figure out if this is a quick fix or needs real routine change.