Location check every 4 seconds

I have SEP 12.1.4100.4126 and want my clients to update from the SEPM when on the network and update from Symantec LiveUpdate server when not on the network. I have set up a second location "External" and clients switch to this location when they cannot contact the SEPM. My question is:

The location will be checked every 4 seconds - that is the default

What is best practice for this location check? To me every 4 seconds seems pretty extreme. Currently I have a small test group but this is going to be deployed to a few thousand endpoints and I don't want them hammering the SEPM every 4 seconds. Any advice or real world proven checkin times?