BA do this, although only in economy I think. It’s a 24 hour minimum too. I’ve never needed it. I’ve booked on fully sold flights in a full fare class a few da

BA do this, although only in economy I think. It’s a 24 hour minimum too. I’ve never needed it. I’ve booked on fully sold flights in a full fare class a few days before and the wait list clears, often in a few hours.