Well... probably never but I did (on LEGO SE). The story would end there if I had not also the knack to build a machine to test it. Here it is:
The first version was using a metal tube attaching the top servo to the LEGO brick. It was too flimsy and died during initial testing. So I took an old CPU heat sink...
And using my trusty angle cutter, I made this new arm:
A successful test proved that the LEGO was no match for this chunk of aluminium. I then made an infra-red proximity sensor to detect if the presence of the LEGO and rigged the whole thing to an Arduino. This was shot before the test started:
and this was shot about two thirds into the testing that lasted a whopping 10 days!!!
So here are the 2 dead LEGO bricks after 10 days and 37,112 assembling and disassembling.
Don't try this at home. It's long, noisy and cruel to LEGO bricks.
In the end, both pieces failed at 50%. The studs of the bottom brick and the inside walls of the top brick are visibly worn. Both bricks can still hold on (not strongly) to normal bricks but, when put together, they can't hold. In a way, you could say that they are still in working conditions as long as they don't meet again.
Here are some more answers: