Certain Daily Quests feature double drop rates depending on the day of the week.
Daily Quest Double Drop Rate Schedule
Mon: EXP Chamber, Gil Chamber, Ore Chamber, Growth Egg Chamber, Pot Chamber
Tue: Alcryst Chamber (Fire/Wind), Esper Awakening Chamber (Fire/Wind)
Wed: Alcryst Chamber (Water/Ice), Esper Awakening Chamber (Water/Ice)
Thu: Alcryst Chamber (Earth/Dark), Esper Awakening Chamber (Earth/Dark)
Fri: Alcryst Chamber (Lightning/Light), Esper Awakening Chamber (Lightning/Light)
Sat: Training Chamber (High Difficulty)
On Saturday and Sunday, the Gil Chamber and Ore Chamber allow unlimited attempts.