If you are using the primary user attribute to define some of your software installations in CM2012 it can be useful to audit the deployed devices in your environment to help troubleshoot issues with application deployment. I use primary user to help define software delivery such as having FAT packages only install on primary devices or have App-V applications only fully cache on a primary device. I quickly put together a query  you can use to check Windows 7 machines to see if they have a primary user assigned or build a collection of machines the helpdesk can look at when trying to troubleshoot application delivery issues.