I've seen some very precarious jack situations including a car almost falling on someone (stopped it), and my brother's Cutlass Supreme fell on him. (He got lucky and was uninjured)
Often mechanics can be dulled to the high possibility of jack failures or weight imbalances. I hope never to hear that one of us falls prey to it.
Thanks for the staunch reminder.
ps, your sig pic beckons me like a warm summer breeze...