I've also been thinking along these same lines, especially as I'm in the process of developing a fitness/diet routine that will work for me. In the past I'd have slavishly followed some one else's system. I've come to realize, however, that everything isn't set only in black and white; in real life there are many shades of gray, which I think is a major failing on the part of some followers of Objectivism. Jorge's final paragraph really hits the nail on the head:

For a free life one needs a set of guiding principles and the flexibility to act. Systems can help in well defined areas, but they are not useful for running one's life.