I'm new to this forum & not sure if what I'm about to share is related to this discussion 'coz this happen outside the dojo.
One of my old buddy in aikido (we were then training extensively for about 4 years in aikido, almost everyday) and it come to a point in our training that we try on several occasions doing randori (at full/realistic speed/attacks…I know, we were crazy then) on concrete floors or on any surface we found challenging to fall, maybe because at that time we were trying to "test" the effectivity of the things we learned (techniques or ukemi) and was never thinking straight of the possibility of injuries.
This buddy of mine went into military service and went further to train into the elite group (scout ranger). Right after graduating the course, he told us about his experience that he had an accident during a particular exercise, wherein they are required to jump-off the chopper at a certain height (about 10 to 15 feet, if my memory serves me right) with full battle gear. However, the chopper was very unstable because of wind factor. Unable to control the required height and stability, accidentally throw my buddy outside the chopper and went straight down. He told us that the only thing in his mind was "I'm dead" but maybe because of the years of practice, automatically prepared himself as if doing a break fall. And went ahead of the training with only a small bruise on his arm. Even his companion during the exercise could not believe what they have witness and told him that he should have been injured with a broken arm "at least" with a fall more than 20 feet with a very rugged terrain unprepared. And went further by saying that "if not for aikido I could now be in a body bag".
Anyway, I believe that there would come a time in our training that doing ukemi or performing a teacnique is just like speaking our second language automatically when needed.