We usually go for one of the last breakfast buffets since it is usually nice and empty and quieter by the time we are done. We have never had an issue with restaurants either not bringing out fresh food or replacing empty dishes. We have been one of the last 2 or 3 tables to leave a restaurant after breakfast and they were still bringing out food even though all the tables were done eating.
CP is slightly different than some of the others since it also has a lunch buffet. Lunch starts at about 11:30 or so and the dishes begin to come out a couple of minutes before then. If you have a 10:30 or so ADR you might have a few minutes where the breakfast selections stop coming out since they will be in the process of switching over to lunch, but you would also get a chance to take from the lunch buffet.