My target is 2 hours or more. If returning to the US and you have a connecting flight you have to collect your luggage and redeposit it. We just did this returning from Lisbon to JFK and connecting to RDU. We also have global entry (one of the greatest things ever). Our time to clear customs, retrieve our luggage and redeposit it was well less then an hour. Customs with GE took about two minutes.