Never bother. (See threads about backpacking weight.) Never even really considered it.
We have a freestanding tent, so that helps. Still have to stake out the fly, though. If I can't drive a stake in by stepping on it, then I assume I've hit a rock and move it a bit. I also tend to get creative with the guy line to find a better spot. Very rarely have I ever failed to get adequate support with either a stake or tie around some immoveable object.