there's also a case where United does a schedule change.
(over 30 min = free rebook, over 2 hour = free refund)
EF says SQ12 95% ontime,
max delay 71 min (just above OP's limit)
(71 min delay)
https://flightaware.com/live/flight/...015Z/RJAA/KLAX
11:50am + delay/taxiing = 1pm. add 30 min for customs + immigration + bags = 1:30pm
10 minute walk from TBIT to T7/8 with luggage, though you have free baggage carts @ TBIT. 5 min bag drop via Premier line = 2pm, then security & walk to gate (2:10pm)
say United shifts it up 30 min = 2:50pm, you need to be there 15min before gate closes = 2:30pm
all this without a potty break. a little rushed for me?