I was wondering if there are any specific airports in Asia/Europe where it is relatively easy to do an MR on a tight schedule because you don’t need to clear local immigration before boarding a return flight to the US. Is this the case anywhere?

How would that process work for SIN.. check in for both flights before departing the US or check in for the second leg online upon arrival in SIN?

SIN is a very easy airport to navigate. I always get all boarding passes, on card stock, before I leave the US. They have a security officer at the transit desk who affixes a sticker to the passport. Due to a tight connection, only once did I have to go straight to another gate. They told me I should have gone to the transit desk, but they took my US minted boarding pass. It’s a very easy airport to transit.

The same would be true for most transborder (USA and Canada) flights.

One more quirk about SIN. I fly from LAX through SFO to SIN on United. It used to be the case that I had to wait until 24 hours before the time of departure of the return flight: UA2 being my favorite. Recently, however, if I ask to print a boarding pass in the early afternoon of the departure of UA1, all four boarding passes print out. When I’ve done back-to-back MRs, I’ve been able to print out everything at SFO for the next trip as I wait at the airport for the LAX leg of my first MR.

Finally, one quirk is if you have status on United and print the boarding passes early, you won’t appear on the upgrade list for the last leg. The solution is to call customer service and have them check you out of the final leg, then check you back in. Poof: you magically appear on the upgrade list.

If I arrive from an United flight, how do I get to T4 for VN flight? Thanks.