My FS always put 2 back in till they realised my cervix couldnt hold a pregnancy so two was just unrealistic. I went back to have a FET done last yr and my FS said why not put 2 back and I had to say NO just 1 LOL ,
This is with MIVF, never had a problem with the number but think it is a FS RE thing that they and the patient decide on.