I've come close a few times, but thus far I've never missed a flight due to my own doing. I really need to get out of the habit of staying in the lounge until the last second though ... the "walk of shame" of being the last pax on board isn't so wonderful
I've misconnected a couple times - the last was doing the SYD INT>DOM shuffle, the time before that was due to a mx issue out of LGA. The lovely AAngels at DFW D got me sorted out though! ^