In response to the first question, in keeping with what my colleague was saying earlier, yes, there can be objectifiable symptoms. If, according to someone, having both stool and urine incontinence is a form of suffering that is intolerable and objectifiable to that patient, who has in fact repeatedly experienced this incontinence, it can be a criterion that could be used to act upon the advance request.
As for the number of times the request should be reassessed, that really depends on each person and the stage they have reached. The process is designed simply to ensure that the wish has remained stable over time and that it factors in all the changes associated with dementia.