What about adding IL speedruns for each board? Same rules as Story Mode (15 turns, all minigames, no handicap, any difficulty, any character), time starts when the host is selected (Story Mode) or the settings are confirmed (Party Mode) and ends when you win and hit "skip" on the results board.

It'd be a lot more accessible for people who don't have time to spend 4 1/2+ hours to speedrun the whole story mode, but still want to speedrun Mario Party 4 to experience the minigames and play their favorite boards.