Man is the covenant head of his household (1 Corinthians 11:3, Ephesians 5:23). This is clear. But how ,for instance, is a covenant head to know if he is "good" or "successful" in his role ? Where does one look ?
Does one look at what society or culture tells him ?
Ok, the Bible is the place to look but all we are given there is an example of a "bad" or "unsuccessful" covenant head. I guess if you simply manage to avoid the bad extreme you're alright. Who is to say otherwise ?
Goes to show how much we really know about "covenant headship" or even how "covenant" operates although there is no shortage of persons telling you how absolutely sure they are how the "covenant" operates (i.e. check out the people of the Federal Vision persuasion for instance) and go from there to confidently affirm "the truth of" paedo-baptism, paedo-communion, baptismal regeneration and a whole host of God's other operations.
I suspect covenant is as complex as creation itself and we should be so confident about how covenant operates only when we have figured out all the secrets of Creation. That should keep us humble for a while i should expect.