The party(s) can be any time. Doing the parties on a Sunday would probably be criticized, and that to me seems a fight that's simply not worth the effort or time. I have no issue in that regard.
I do think that it is unnecessary when the person has been re-elected and is already sitting in office, though. Even if it is private money, it seems like a waste to me. Then again, caterers and other party support people could use the work, so I guess it's not a huge deal.