Persona 5: The Phantom X had a hard time doing away with the series' iconic calendar system: 'It was very difficult to convince the team'
Persona is a series defined by its calendar system. Everything revolves around it: the school schedule, dungeon deadlines, and social events. So what happens when you try and stuff that core gameplay system-shaped peg into a gacha-shaped hole?
Well, you don't. Instead, you remove it. Persona 5: The Phantom X still retains some kind of calendar, but set dates have been swapped out for a far more vague "yesterday, today, tomorrow" system. It makes sense for a game that is constantly shifting and changing with story and character updates...