If you want to turn em, go here for the method I use: http://yarninhand.blogspot.com/2012/03/reversible-two-sided-granny-square-best.html
Ever so many patterns (soooo many) I've seen for granny squares are worked in one continuous round, with a front (right) side and a back (wrong) side. Most require an initial color, a color change at the second round, another at the third round, so on and so forth. Very traditional. No doubt, you've seen them too. While these are great and all, when you're making a blanket, which shows both of its "sides" there is a better way...make it reversible.
When I "learned to granny square" Betty turned after every round...and at the time, I didn't question the method--I did not know anything different. It is only in hindsight after many years crocheting that I realized I had not been taught "the norm." Frankly, I prefer to turn my squares, making them reversible with a much more pleasing appearance; unless they are being used for something one sided--to cover a pillow, to make a purse, etc., where you only need to see "one good side."
Of course, if you are working on a different type of "granny" motif, which could possibly no longer qualify to be categorized as a "granny" - you don't have much choice as to the one-sidedness of the process, as that would be a pertinent part of the pattern. Still, when I have the option, I will turn my square.