This may have been brought up before however as I am doing the Otherworld Exploration in S2 I have noticed that there are 3 areas to try to get to 100% in order to get the buffs for the final season boss.
The issue is that there is no cap on how many times people can do the Chaos Shadows as long as they are different teams. Seeing this give the most EXP which adds to getting more Echo of Clepsydra people are less likely to contribute to the Adventure Preparation quests or the Elemental Domains as they don't give much EXP. All of this translates in the final boss buffs only coming from 1 of the 3 potential buffs.
Perhaps a cap can be put on the Chaos Shadows same as during the season with the Continental Challenges to 1 saved attempt per boss. This will make people do more of the other 2 areas and make it more likely to unlock all 3 buffs ready for the final boss.