I have a P4, and I have had the smart RTH switch in DJI go toggled to off for as long as I have had my phantom. When I do long distance flights, I still get a battery warning at ~60% that tells me I need to come back, gives me the ten seconds, etc.
Based on this thread, this shouldn't happen unless I had toggled on the smart rth switch in Go. At this point, I have no idea what the smart rth switch in go does or why it even exists.
I'd like to get clarification on this as I think it's very important to know RTH inside and out because it could be the difference in a crash.
Are you asking what toggling the switch on or off actually does?