Final answer:
The Public Report is valid for an initial period of six months, with the possibility of extending it up to three years if there are no material changes.
Step-by-step explanation:
Once the Arizona Department of Real Estate (ADRE) publishes a subdivider's Public Report, assuming there are no material changes, the Public Report is valid for an initial period of six months. After the initial six months, the subdivider can request an extension for up to three years. This extension is granted if there have been no material changes to the subdivision's plans or other relevant information.