SE should make it so that your reward is reduced if you join a party in progress.


You complete half the dungeon? You get half the exp, gil, seals, tomes.

You complete 3/4 of the dungeon? You get 3/4 of the good stuff.

Complete the entire dungeon, you get it all.



Granted, that might make fewer people click on the "join party in progress" button in the first place, but, if you're only doing 1/4 the dungeon, you shouldn't expect/demand to get a full reward in my opinion.