Is there really an International Chest Day? Hmm... probably.
I'm not a member of a gym, as I spend too much time on the climbing wall. But I do try to keep my upper body in shape by using the pull-down machine at an outdoor gym near where I live. It's probably not as specific as the one you're using, but it helps. It's not just my chest that benefits - it also helps my upper arms and upper back look more defined and shapely, and best of all, it helps me climb :)