I hope my experience last week may help someone else.
As I was stuck in traffic on the way to LAX, I was thinking that missing a flight had to happen to me sooner or later, although I was also thinking, that afternoon flights are almost always delayed anyways so it'll be ok
I got to the Avis rental return at LAX 20 minutes before my scheduled AA flight.
I returned the car, and got on the shuttle bus. I asked the driver if he thought I would be able to catch my flight that was in about 15 minutes, and he immediately called another person to drive me there separately.
So I'm chaffeured to the terminal about 10-15 minutes before flight time, run inside and don't see my flight on the departure screens!
As an Aadvantage Pt, I run to the FC checkin, wait a couple of minutes, and get checked in, thinking also that at least they'll know I'm here. I get checked in, but I was also advised that I should have gone directly to the gate, but I explain that I didn't see the flight listed.
Anyways, I then ran up the escalator, and after x-ray, security, for the first time ever anywhere, asked me to open my carryon for inspection!
Fortunately that took only a minute of poking around, and I run to the gate, which of course, is never one of the closest ones.
As I approach the gate, I hear my name being paged so I stop at the counter, unnecessarily as it turned out, as I'm already checked in so I could just proceed to board.
I board just before they close the gate, and wonder of wonders, find space for my carryon in the overhead by my seat.
Plane departed on time, and arrived a few minutes early at SJC.