I think that could be done depending on how the condition progresses. It could be every five years or a little less than that if the condition evolves very quickly. There may not be any absolute rule, but, yes, it could definitely be done at least every five years.
I think it would be wise to provide for requests to be reviewed because circumstances change. We have a lot of data on experiential knowledge and on the way people's perceptions can change following an announcement because they ultimately grow accustomed to certain things. People may not change their minds in the end, but they must have an opportunity to review certain choices.