Well, you kind of have to play it by ear - I add shavings every day, but by the time a week is up it has to be totally changed out. In the interim, when I take the feeders and waterers out, the chicks have a blast pecking around where they were

If you think it's getting too wet or smelly before that, change it sooner, and if in a week it still seems pretty fresh and dry, give it another day, and make another decision.
Chicks and chickens don't read the books on raising them, unfortunately, and some things you just have to follow your instincts on. When they are wrong, you learn, like it or not. It is a lot like life - just because something isn't supposed to happen, doesn't mean it won't, you know? The more you watch them the more you will instinctively know what they need/want. The fact you are spending so much time with them will help you determine what is best, regardless of what any book or poster tells you. I've tried lots of things that sounded great that didn't work out that way for me. Sometimes it was because the recommendation came from someone in a very different climate, sometimes it was just because the flock dynamics were different, and sometimes it's just dumb luck that what worked for one person didn't work for me. The whole experience teaches you in a general sense that the world may or may not share your concept of your future, and that nothing is as predictable as we would like it to be. You might be the person that learns to just roll with it and accept that it is the way of mother nature, and you might be the person that decides the sometimes life and death decisions you have to make to be a chicken keeper are not for you. Either way, you learn something about yourself, and often those around you.