You wouldn't so much keep adjusting them as you would keep them rigid. In theory, if your leg muscles were strong enough, you could plant your feet a metre apart and still stay upright (skaters and cheerleaders can do this). You would not have to "keep adjusting" anything - likewise, a perfectly solid statue of a man would stand like this just fine with no sliding.
But, the problem is, that is not the way we stand. I'd be happy to direct you to a number of postural studies if you're interested.