Yup, I agree. I almost had the "can't get out in time" moment myself when one of my cleats became
really loose but fortunately it worked out. I have fallen twice, however, not as a
direct result of a cleat failing to release, though it was a contributing factor. Once I was riding my mtb on a trail and encountered deep sand. I went from 12MPH to 0 in seconds and couldn't get my foot out in time. Fortunately the landing was soft due to the sand and nobody saw.
The second time was just a few weeks ago - also on my mtb - but riding in the city with friends. I bunnyhopped some bad sidewalk but managed to land in another crevice (between two cement slabs) just wide enough to lock my front knobby in. I endoed into a guard rail but did manage to get my left foot out!
My chin smacked the aluminum rail pretty hard and I was expecting blood to start gushing. Fortunately it didn't and I escaped with only a few cuts and bruises. I think my friends enjoyed the whole scene but they did manage to hold their laughter (but only until later, probably!). After it happened, my right (the direction I fell) foot remained clipped in and I felt somewhat like a turtle on my back. One of my friends rushed up and asked if I was alright and my response while trying to get up was "I'll let you know in a minute..."