Again a lot of interesting opinion and anecdotal evidence. I just know almost all the great players were great blitz players so it can't be harmful. If you look at the great Herceg Novi blitz tournament, 1970, which Fischer won 19 pts out of 22, in which played Petrosian, Korchnoi, Bronstein, Tal, Smyslov, etc, Fischer's two great attributes, speed and accuracy came to fore. This is what blitz helps. As all blitz players know, you could be playing a masterfully strategic game and suddenly you drop a piece or a couple of pawns and everything's downhill from there. You gotta have quick sight of the board. I stink at blitz, a little less stinky at correspondence, but I can sense in a blitz game over the internet that even tho my opponent has a superior position, he's beginning to hesitate in case he loses that position and he slows down. I try to keep as much on the board as possible and play quickly, trying to use his time to choose my moves. It doesn't hurt, in my opinion, as long as you realize that that this sort of thing doesn't work in OTB, unless your time is really short. Again, I wish that some chess psychologist would do some sort of double blind study to find out what works and what doesn't, as all this is personal opinion and usually contradictory.