Whenever I flew LAX-SFO-LHR, UA always wanted me to do the 55 minute connection. Knowing SFO I knew better, and would ask them to route me on an earlier flight. I'd rather sit in the Int'l RCC for extra time surfing FT & having a drink than miss the flight to LHR. Sometimes the fare was the same; sometimes going early would jump it significantly. If it jumped it significantly I'd stay on the original but ask re: the load & go early to LAX/do standby anyway. I always made it. I was willing to lose the upgrade on LAX-SFO (although that never happened luckily) going standby in order to make sure I made the int'l flight.

Something I also learned from sandiego1k, who learned it the hard way from UA, is even if you're on a same flight #, if there's a delay on the originating, they're not holding the onward for you, unless there's a gazillion of you. I think that happened to her a few times going SAN-SFO-XXX. Heck, coming back on UA947 which connects at IAD, 947 IAD-LAX went on w/o us, even though a LOT of us on the AMS-IAD folk were on the onward. We had gotten stuck at Shannon due to a medical divert. I called UA from there & at least got on to the last flight of the evening (unlike most of the others), but even though there were quite a few of us UA didn't hold 947 for us (maybe due to immigration?).

Since I'm now based in the Midwest & will get to deal w/ the joys of routing through ORD, I'm sticking to my plan of getting to ORD on an earlier flight rather than take a chance on missing the onward int'l flights. There's a reason I saved up all those RCC drink chits

Cheers.