The irony of TBIT arrivals is that they are still scheduling connecting flights as if you were arriving in T6, so I missed a connection there a couple of weeks ago by miles. Immigration was a disaster, and stupid me, I still hadn't sorted out my global entry program thingy. I've fixed that now, you can be sure.
LAX has much better upgrade availability than SFO, by several country miles, so in truth there is lots to be said for flying through there right now. But TBIT is a nightmare; the baggage drop off is a workplace hazard right now. Ah well ...