I was on AA 182 PVG - LAX on Oct 5. We arrived at a gate in TBIT. The gate was connected by a jet bridge to the terminal so there was no need for buses. Walk to Customs and Immigration was under 2 mins and there wasn't much wait around 6pm. I had a connecting flight to JFK so after I cleared customs I dropped off my bag prior to leaving TBIT. The walk from TBIT to T4 was fairly short probably 1-2 mins. The whole process took less than 15 mins.