Had cataract operation which was the assembly line operation you described.

For the second eye I was the second patient in the morning. Waiting in prep room after being jabbed. Could hear some commotion in the next room. I now know the ‘microscopic’ they look through to do the operation is run by three AA batteries and those in the machine had gone flat with no replacements in the building.

Someone had to run down to the corner shop to buy batteries before the show could go on. At least it was before not during the operation