To tell you the truth, your hair growth isn't that unusual. Last week, my friend and I got our hair done and today, I saw a bit of regrowth on her roots already. From what I learned in cosmotology school, your hair growth is average.

Most TINTS (it's against the rules for beauticians to call it dye) are basically the same. They all consist of the color and the developer. If you are trying to lighten your hair then the volume of peroxide (developer) is important, but not when you are tinting it dark. There's not much you can do about your hair growth, so maybe going with a semi-permanent color more often would be better than waiting four weeks for a touch up.

Another advantage that semi-permanent colors have is that you can do your whole head at once; no sectioning and being careful to stay on the regrowth only.

Hope that helps.