".........................this yesterdays (non)event gives you an idea of what I am talking about. And you have to save 1% of fuel on quite a number of flight to compensate for the cost of such (non)events, including a cancelled flight with 100% of unsatisfied customers and 60% of dumped fuel."
With very few exceptions, the wings are folded and locked before take off, not after. So, unlike a landing gear malfunction after take off, I certainly don't see where anyone is going to dump fuel on account of flying an aircraft with folding wings.
That's not to say that the occasional U.S. Marine aviator hasn't taken off with the wings folded and been forced to dump fuel, but that practice is strongly discouraged; at least it was in the Navy. Plus ex U.S. Marines aren't allowed to fly airliners anymore ever since the Flight Attendant's Union decided that the plots could no longer force them to "DROP AND GIVE ME TEN YOU MAGGOT" when the coffee was cold.
I have folded and extended the wings countless times on various Navy aircraft and while I'm sure that nothing is 100% reliable, I can't ever recall a wing fold malfunction. I do remember a time or two when the indicator system failed to confirm the wings were locked, but a quick visual confirmation is all that is required before take off. I'm sure the 777x will have that provision.