One week is perfectly fine imo since the weekend may be needed for some players with different timezones to arrange a time for the battle.
Rounds should be announced on mondays as well imo.
-1
First of all its below 130s and not 120s which seems well balanced since a lot of players already finished the quest successfully. You just have to figure out the strategy behind it.
180s seems way to easy and would mean the quest would be no challenge at all.