I think once or twice on a 7 night cruise would be more than plenty.
I actually feel a bit embarassed for the less-outgoing employees to have to do that.(Some employees do
get into it though.) They are wearing nice serving outfits. I think it looks a bit tacky when they do it.
I was actually going to write a letter to Carnival to suggest cutting back on the number of times they do that, but never did. We actually only suffered through it a couple of nights as we had finished our meals and left before the 'fun' began. Even my daughters thought it a bit strange. We did get up and dance on the last night with our sweet Assistant Waitress-felt sorry for her.
But I am glad at least some people enjoy it.