"Being able to take up or resume in the middle of a tune is a skill in itself"
I watched a recent Leonard Cohen broadcast* and was impressed by his stopping to talk in a song then continuing. It isn't easy. If I think of a 'witticism' then continue I reckon restarting that verse is a help to me and the audience as you can't afford to lose them in the story of the song. Less important I suggest to the hearer of a tune or watcher of a dance.

(* on someone else's TV if the Licence people see this. I don't have one.)