Is there a best practice or are there sizing concerns that are recommended for setting the frequency of replication?
NOTE: Symantec provides this information as a general guideline. Conditions for every environment are different which may effect the overall performance of replication.
As in any replication environment, the interval of replication should be set so that overlapping replications are avoided. The larger the environment or the more data intensive the replication, the larger the interval of replication should be. If the amount of data required by replication causes the replication time to exceed the interval of replication, severe performance degradation of the Endpoint Protection Managers can be expected.
To determine a good frequency for replication observe how long it takes for a replication to complete by reviewing the System: Server Activity logs (SEPM -> Monitors -> Logs tab -> Log type: System -> Log content: Server Activity -> Time range: Past week -> View Log button). In these logs the time of replication start and completion is logged and time stamped. Make sure that this time from start to finish is always well below your configured replication interval. The least frequent manual setting for replication is one hour. Note: If Auto Replication is selected then replication may occur as frequently as every five minutes.
Also see: How To Optimize Endpoint Protection for Branch Offices using GUPs, Load Balancing, and Location Awareness