A complete Living Will indeed does contain a number of different documents: an Advanced Healthcare Directive document, Durable Property Power of Attorney documents, a HIPAA Medical Records Release Authorization form, the Notice of Final Disposition document, etc.
Sometimes these documents are provided separately, sometimes they are folded into one long document.
If all of the documents listed above are combined into one single document with one set of signature lines, then a single notarization should suffice to cover them all.
However, if these are separate documents with separate signature lines, each document should be signed and notarized individually.
To find a well-crafted document set with all of the required forms, see Standard Legal’s Living Will package here.