The arbitrary n days a week requirement is just a simple lazy way of ensuring people visit the buildings consistently so there is a valid reason to keep them paid for. It will also continue to be n+1 until things return to as they were or peoples investments are no longer going to benefit with more forced return to office.
Face to face meetings can be organised anywhere. Its just inefficient to be using a building and requiring people to travel for what does mostly amount to sitting on your own on teams calls anyway. The requirement to have people sitting in places where you occasionally bump into them just smacks of bad management.
In person meetings can be useful for improving social relations. Mandating n days a week on the off chance you might have a useful meeting is asinine.