This is the old way of cooking - waste means you have to go pull it out of the fields or kill it yourself.
Honestly, its a sign of a great (and often family or locally run) restaurant when I see they are rolling their menu into the next day in a circumspect way - its a sign to me that they understand their menu very well and know the best ways to present it.
My father had a restaurant long ago. He hired a professional and prestigious cooker (the the title "chef" was not so common then) and the first thing he noticed is that everything was used.
There were a thousand tricks to plan the menus so meat not served were reused for broth and so on.