We ALWAYS get on of the very last seating for breakfast buffets (we like to sleep late, plus we treat it is a brunch rather than just a breakfast) and I am amazed how I have NEVER felt rushed, never saw them cleaning up around me, or leaving old food on the buffet line. They replenish food even after the last ADR time. What they do sometimes is, they allow a section of the restaurant to get empty, and also if the buffet has 2 sides with the same items on it (like Chef Mickeys, for example) they will shut down and clean up one side.
Late breakfast ADRs are our favorite, and really make us feel like we are on "vacation!" Enjoy!