No, but they would've updated it when they could've, and "hey, two years ago I said I wanted this" has more weight than fighting family members or something determined 60 years ago. Hence the regular updating (I'm thinking like every 5 years or so for a healthy person and the person can change it sooner if they want, and are encouraged to when health concerns arise).

I would say the person in question would have to be in the mind to be able to independently fill out and update that wish without being easily manipulated against their wishes, so that say a person's state of mind deteriorates and a family member encourages them to update it, the person is evaluated without the family member present to see if they are capable of making that decision.

Of course there are going to be those who are not able to make that decision at all from the time they become an adult, but generally they would have a guardian who is trusted for all other decisions so I can see being unideal depending on how good the guardian's intentions are and the relationship between the two.