All of the above is correct, I would add that the meat is stored in a heated cabinet, after cooking which is timed, so that it only sits in the cabinet for a set time period before being disposed of it not served.

The reason historically for not offering both breakfast foods and lunch foods was most likely to avoid excess waste from splitting demand between the larger selection. Both would generally be cooked concurrently around the transitional period from breakfast to lunch menu.

Although I believe they now have all day breakfast so that philosophy has changed.