Hello,
I understand what you have been through.
After creating Threads Again and Again, I am sure you may have something behind your mind. It seems, you are not receiving a Answer what you are looking for.
I see, you had already created a thread:
https://www-secure.symantec.com/connect/forums/sep-xp-vdis-any-special-special-policy-considers-and-update-time
If I am not mistaken after reading both the Thread, I found your expectations are:
1) Looking for Best Practices guide.
2) Policies for Liveupdate and so on for your VDI environment.
3) configure a randomize window for AV updates and change the weekly scheduled scan to mid night
Please check the Articles provided below to answer all your questions.
1) Tips for reducing the impact of SEP in VDI infrastructures
2) Best Practices for Symantec Endpoint Protection in Virtual Environments
http://www.symantec.com/business/support/index?page=content&id=TECH95300&locale=en_US
3) How to prepare SEP clients on virtual disks for use with Citrix Provisioning Server
http://www.symantec.com/business/support/index?page=content&id=TECH123419&locale=en_US
4) Securing Virtual Environments - Best Practices White Paper
5) Windows XP logoff hangs on 'Saving your settings'
https://www-secure.symantec.com/connect/forums/windows-xp-logoff-hangs-saving-your-settings
Hope you get all the answers here.