If i use SEPM and select distribute upgrades over 7 days how does it work?. Will it end up in success ?
Yes,You must test the AutoUpgrade process before you attempt to upgrade a large number of clients in your production network. If you do not have a test network, you can create a test group. You can add a few non-critical clients to the test group and upgrade them by using AutoUpgrade. You can confirm the upgrade completed successfully by verifying the version number of the client software that appears in the About dialog box.
Upgrading clients by using AutoUpgrade in Symantec Endpoint Protection
https://www-secure.symantec.com/connect/articles/upgrade-clients-sep-121-auto-upgrade-feature