There aren't all that many Americans who can tell you without taking a minute to think exactly what time 20:25 is. Russia, however, uses the 24-hour clock much more frequently than we do in the US. Maybe it's related to the militarization of Russian society, but people use the 24-hour clock even in casual speech. Americans--try to tell your friends you want to meet them at the bar at 21:30 and see what happens. 

My stint as a bus driver got me very comfortable using the 24-hour clock--I had to be able to instantly know what my supervisor meant when he said, "I need you to relieve CLS at Carmack 1 at 16:29." It took at little while, but I feel totally comfortable using the 24-hour clock. My students, of course, have little conception of what AM and PM mean: Russians also use the 12-hour clock in conversation, but they say things like, "Let's meet at 9 in the evening." What's interesting is that Americans generally just say, for example, "The movie starts at 9," and we understand that of course the movie is in the evening, whereas Russians almost always will either use the 24-hour clock or specify that the movie is at 9 in the evening. I guess the Russian way leaves less room for error, although I've never had a problem with the American system.