The way I understand it, even if you're capable of it then the attempt is not merely coming up and doing it, but hours long process of warming up through smaller flashes.

In one European juggling convention ages ago Albert Lucas made I think 10 rings flashing attempt scheduled at particular hour. Hundreds of people gathered around and he got an extreme round of applause for flashing 1 ring. The he flashed 1 in his left hand. Then 1 in left, 1 in right. Then 2 in one hand, etc.

By the time he got to 10 most of the audience left, and there was just a handful of people witnessing the actual success.