I think it can as long as you're aware of the differences between a sport fight and a real fight. I don't have any firsthand knowledge, BTW, just going by what I've heard, read, etc. Our teacher has told us that one potential problem in training for sport then using it for self defense is with pulling punches and kicks. It's great for sport so you don't beat your opponent to death, but you're training your reflexes and instincts to just miss the target. He said if you train like that, when a real fight comes along, you'll always be missing your opponent because that's how you've trained to fight and it's now become instinctive. If you want to hit your target, you have to train by hitting your target. He's said when we get far enough along to reach a point where he can teach us combat stuff, we'll get training gear to wear and practice timing and distance stuff while learning to hit our targets. He's also mentioned things like some MA sport competitions (possibly TKD, but I don't really remember offhand) make certain areas of the body illegal to hit, e.g. the back. So people in sport fights can get away with turning their backs to their opponents and they won't get hit (or at least scored upon) because the back is an illegal target. Again, the idea is if you train that way so much that it becomes instinctive, you may do it in a real fight, but there are no rules there and someone can nail you in the back when you turn like that. I suspect almost any training and knowledge is better than none, but I think you have to watch out for differences like these.