When to use part time or full time 4 wheel drive?

I know what 4 lo is and I know that 4 hi full time has everything locked in and 4 hi part time doesn't. What I don't know is when to use part time and full time high?|||When you lock in 4x4 hi or low all wheels turn as 1 and it is lard on everything when you do any turnig. Only use when needed like getting un-stuck only AWD all-wheel-drive has slipage between the wheels when turing unless you put it in fulltime 4x4 high and low. Hope that answers your question.