Originally Posted by SQ325

SQ blocks the first few rows in Y for their Top-Tier FF. If you are belonging to that group, you will have no problems to get the seat you want even for last minute bookings. They will be (partially) released when OLCI opens.

SQ is clearing the dummy seat reservations 72 hours before departure. Usually then you will find better seat availablity. Not sure if it has to do with the software, but i feel if the seat has been allocated once it wont become available anymore until 72 hours before departure, even when you change your seat.