When your security gets unruly, it can get time consuming to figure out how a user is accessing a SQL instance. Sometimes you may know that a user is getting access via one certain AD group but you aren't sure if any other groups are granting access. Furthermore, a user might be in a group that's nested in another group, through which they are gaining access to your SQL instance.
Maybe this is a one-off type of thing, but if you need to see every folder within a directory and get the list of who can access that folder, it can be done using PowerShell. The output is tab-separated and can easily paste into an Excel sheet.