If being told to hold position is for mental effect, then I am all for it. A Top saying, "you better not move!" - knowing full well she will be moving, but it's the "oh no! I moved" feeling that a bottom can get after having squirmed, and the amusement of the Top as he jokingly chides her for it and gives 'extra'...
But to seriously be expected to stay still...nope.
sarah