Yeah sometimes the agents announce that, that things COULD change, and you need to keep checking the board. Also, they should do a page at least in the terminal if things change. But if you leave the terminal you will be out of luck and you need to pay close attention to the boards and sometimes even that isn't good enough.

I'll usually just camp out at the gate or nearby gate with CNN, get some food, eat it at my seat, and read a book or something but stay within earshot!