Hi! I like to stitch by color, this is commonly known as cross country stitching, I stitch where ever the color takes me and for as long is I feel like stitching that color or until the next stitch is just to far away. The other method of stitching the area and "parking" your threads is just as good for some people. but I can't seem to keep all the threads organized. As far as which is faster i think all depends on you and what you are comfortable with, it's just a matter of personal preference.
I like to stitch by colours in the area of the hoop. I generally start stitching with the colour which has the most visible chart symbol so it is obvious to see - this really depends of the symbols that are around, but I just choose the one that catches my eyes. I have less chances to forget a stitch or to misplace it. When a zone contains similar colours, I will stitch the darkest one and then the lightest one and then go on with the intermediary colours, having yet various points of references. This isn’t a faster method, but an easier one for me so it reduces the time undoing wrong stitches.
Obviously, I don't do this to the original pattern. But I make photo copies, and cut a small section of the pattern off, normally a 30x30 square section. I tape that to a piece of scrap paper, then I actually sew the scrap paper to my fabric. I use q-snap frames so it's held taught. Then I pick a corner, start with that color, and do all of that color in the section. I go on to another color, and then around the whole pattern. I make fewer mistakes by eliminating how much counting has to be done.
oic... thats a good method... cos when you stitch 30x30, you will see quickly how the thread blending goes and when it looks cool, it will be encouraging to finish the work soon...:)