Am puzzled by this as well.
In CE cabin I've had one CC come out and ask row 1 what they want to eat and drink then pop back to the galley with the order and their colleague starts preping it, they pop back out and take the next rows order by which time row 1's food / drink is ready and it get's brought out and then they take the order from row 3 and back to serve row 2 and so on.
During all this bread basket will make an appearance as well
In my experience it all works very smoothly with no undue delay.