I saw a few problems but it was mostly/all from people just turning off their brains when on-board. So many times I'd be in line watching ahead and folks seem bewildered with the buffet: "what do I do?". "Do I like this?" "Hun, what do you think this chicken-looking thing might be? (Sign says Masala Chicken....).
Other big problem is people piling up plates like they're building the Empire State building. Get a reasonable plate (less food, faster loading) and move on. If you liked something a lot, go back for seconds (hint, they don't run out of food). I lost count how many times I saw heaping abandoned plates on tables (actually witnessed a family sit with three plates, kid takes 1 bite and says "this ain't no good" and they all left). What a waste.....
As for popping in: who cares? Again, lots of food. I'll ask to sneak in and grab a milk/salad. A few times I just went around salad builders because they were the ones holding up the main buffet line. Also, line is too long at 1 buffet section, check other side of that section or go to the other section.