Hello,
Thank you for posting in Symantec community.
I would be glad to answer your query.
Enable the scheduling of automatic downloads from liveupdate servers. The schedule settings do not control downloads from the default management server, from Group Update Providers, or from third party content management tools. Downloads from the default management server depends upon heartbeat interval and selected mode. (Push mode or Pull mode)
Check these articles:
https://www-secure.symantec.com/connect/articles/configure-liveupdate-run-client-updates-when-client-computers-are-idle
https://www-secure.symantec.com/connect/articles/configure-liveupdate-run-symantec-endpoint-protection-manager-sepm
Following KB's can be helpful as well:
Configuring the LiveUpdate download schedule for client computers
http://www.symantec.com/docs/HOWTO55287
Configuring client updates to run when client computers are idle
http://www.symantec.com/docs/HOWTO55289