You really had a bad time with that.
Usually, the omelettes are 1) walk up and order, 2) receive a receipt, 3) hand to a passing waiter, 4) the waiter delivers.
If you order first, then pick your other food and go sit down, a waiter will appear, take your receipt and deliver the omelette almost immediately.
When it's really busy, you might have a problem with the waiter appearing in a timely fashion, but generally not a problem if you go to the buffet during off peak hours. First thing in the AM has worked for us (we're early risers).