Yeah, that's something I think we so often ignore when talking about how well player xyz hit that changeup/curve/rise/etc. At a camp the JMU coach was working with the catchers and she spent a good portion of her time going over how to block the view of signals. She said her (the coach) main job during games is to steal signals. She went so far as looking at the striations in the forearm to tell what fingers were being displayed. So I fully believe there are many times college and even pro players know what's coming. I've been known to give basic cheers to my DD that lets her know a change is coming. I don't always as I want her to hit anything given to her, but in certain situations she "might" get a hint. I take pride in learning the opposing coach's signals. Usually within one inning I have every pitch and location he/she calls, even if they're using cards.
At what level do you think most girls on team can use the information in game speed? I coached with a guy who like you could figure out the signs. But when you player name (fastball) or number (offspeed) very few could actually process and use the info. I know some coaches watch for catchers to set up early and holler either "go with it" (away) or "turn" on it (inside). But at game speed girls hear " wha wha wha wha" like Charlie Brown cartoons.