Let's assume for a moment that everyone is equally lucky--that everyone's net luck sums to a neutral, being neither positive nor negative. That said, if someone did everything in their power to have bad luck for a week, it is probable that the next week they would have relatively decent luck, to balance it out. In this world, instead of knocking on wood, finding four leaf clovers, and bedecking oneself with tokens of luck far in advance, one would do this as close as possible to an anticipated event where good luck was required. And far in advance, one would be walking under ladders, dealing with black cats, and possibly breaking mirrors, depending on how much foresight one had.
Sadly, luck is not so predictable. And gratefully, not so neutral. I feel like I have amazing luck--I found 12 four leaf clovers in an hour once, and there haven't been any negative repercussions.