The asking is pure signalling. Never once did anyone actually say to me that they wanted the last piece. Like adding please, saying good bye or thank you.

I was just referencing the OP wrt conversation. However, I still consider it wasteful and impolite, since it's not merely a polite-sound attached to another message. It's a complete attention-getting, conversation-interrupting message in and of itself, with, apparently, no content.