Luck, its a intangible thing we believe in. We keep saying good luck bad luck for what small flashes of good or bad things that happen to us occasionally. It can be called flukes also but if it happens more than 1 time on either side it cannot be a fluke. Back to the point though. Luck is something we count on every-time we go on to do something. Like select a question paper from a set and hope for the questions to be the ones you know best. But the bad luck factor equalizes the good one. and that bad luck can cause great damage at the wrong times, for example losing your submission work right before an exam on it. I guess we can continue to believe on luck but never over depend because it can hurt you as much as it can help you. Well best is to do everything properly and prepare well and always have a contingency plan for everything you do because this intangible force can hit anytime anywhere.