I would like to know any reason behind the request, I always perfer to upgrade SEPM manually even there is one auto update available. The main reasons are
1) I do not update SEPM often, even there is a newer version released by Symantec, I will evaluate it to decide the fixes are necessary for my SEPM, or if this is just for the clients, then I can only import and export the client pacakge to upgrade the clients only.
2) I would like to have more visibility during the upgrade, there are countable management servers in the environment, thoguh it takes more time to upgrade manually, it is safe and easiler for me to troubleshoot the issues in case there are any, most importantly I do not want to lose my SEPMs if automated upgrade failed.
3) Upgrade SEPM need to break the replication if you have it configured
4) Upgrade requires proper sql account privilege, in the enterprise environment, the database team normally manages the SQL database, they remove some of the unnecessary operation privilege and you will need to request that at the upgrade time.