Well I know that there are many applications including backup software, antivirus, logging applications that do modify the "Last Access" date. Any viewing, copying or moving of the documents, images and other files automatically alters last accessed date stamp of the file which then invalidates using it.

My old script for computer software inventory does similar to Arends but attempts to remove duplicates (have not tested Arend's code but it may already do it) as you will find duplicates in that list.

But using FSO for Last Access Date will be unreliable at best.

There are some WMI scripts that can also monitor application launch that you could probably look at implementing.