19:30 PM in Moscow is 23:30 in China, so it is hard for people who feel sleepy early (like me) to take part in the contest...
I've noticed that at times there will be contests on 11:30 AM Moscow time , which is a favorable time for me and perhaps more students in China. Hope there could be more early contests so that I can increase(drop) my rating :)
11:30 at night? I'd take that over 3:00 am (which is what happens in the Eastern U.S. with the 11:30 am Moscow contest you mentioned ;))
So I suppose if the contests could be held in a variety of time periods, all contestants from the world will be happy, just like GCJ Round1 does -w-