Whenever this gets discussed, increasingly nowadays due to reducing the meal numbers towards the actual numbers of pax, there are always those who say "ah well, we can't carry 50 sets of every choice, you know", as if this is somehow the ONLY option beyond carrying 20-20-10 and then saying "tough" to the people at the back of the cabin.
For what it's worth some years ago carriers used to be able to handle it well, knew what the averages were, knew how many overcaters to put on (not a huge number, but a few), and the issue rarely arose. It is quite possible. Excessive cost-cutting zeal has wiped this out. In times past they did NOT carry 50 of everything.