Well once they've sent room ready text with #, true, they won't change it. But if you are flying and take ME and they know your arrival time (and if it's late) they won't send text until later so they have plenty of time to swap rooms around. If you're driving in, they look at the arrival time you put on the online check in. I admit to always putting earlier than my expected time...like if we think we'll get in at 3pm I may put 1:30pm. If we were to get in at 10pm I'd put 3pm just so we get assigned our room by 4pm and get the text. If you put 10pm, you may get the 4:30-5pm room ready texts (we've gotten about 3 times) and then it may be last available room.