Needs to be a 20 min cd timer if..

[Niwashi]

I think the best solution would be to have the people who clicked the confirm button remain together in the party-to-be. So we don't have to click that confirm button over and over and over, untill all 4 - 8 - 24 have clicked it. The whole queue should never be reset simply because one person decided to withdraw (for whatever reason).

If another party member is added to fill the gap immediately, this would make sense, but what if there's a bit of a wait before the group fills up again? The fact that you're ready now doesn't necessarily mean that you'll be ready five minutes from now, not if in the meantime you've changed classes or started something else. I think that's the reason for repeating the ready-check with each completed group.

Then limitate the 'join to an already started party' to once per day, or twice. That way you finish with this problem, because that people wouldn't even keep trying to withdraw, it would be pointless if they already joined twice that day, because there won't be a chance they could join to an already started duty anymore.

They'd have to be careful not to overdo a solution like this. If they make it significantly harder to join a party in progress, that also makes it significantly harder for a group that's left short-handed to get a replacement party member so they can finish.

Besides, a daily limit would still allow the sort of repeated-withdrawing pattern the OP discussed when a player hasn't reached their limit yet.