Filler-up
When serving 3,000 guests over two seatings in 4.5hrs you have to
a) make everything ready at the same time and
b) make sure there is enough for everyone.
The ship did both of these things exceptionally well as you could order anything and not wait longer than a few minutes for it and you could also have as many of whatever you wanted. So you could order 5 steaks or 3 appetizers or whatever -am sure they would perhaps look at you oddly or the maitre d' would ask if you were consuming so much for a particular reason but you could do it.

For point b) the way that there was an abundance was the fillers they used.
The deserts seemed to have cream in everything so a gelato which has no cream in it had cream to make it bigger and fatter. Little cakes that were supposed to be filled with cheese had cream in them too so they were fluffier, the list went on with substitutions of real ingredients with fillers. So if you were keen on something like a apple rhubarb crumble, the filling was not apple and rhubarb there was a filler of some sugary concoction and and a little bit of apple and rhubarb.

The buffet was also filler-fied. It was filled with a huge section dedicated to salad - so a mound of salad greens, sliced carrots, olives and 4 large containers of salad dressing - fillers. No other condiments for your salad - tuna, corn, tomatoes, beans or the like.

As I mentioned I do not do well with buffets as you pick and pick and somehow don't seem to eat a proper meal. But hey, when can you get a very full Elvis dancing around your dinner table and getting the dining hall up and dancing between courses?