Anyone shut down an engine to extend holding time? e.g island holding or unexpected delay. FF with one off is less than all running
IF you refer to shut one down while airbourne, I expect the relevant regulatory authority would have a say, and the answer might not be to your liking.
Years ago, DanAir requested enroute shutdown of one on the Comet 4, to save fuel, and the ARB (as it was, then, now CAA) replied with a definite NO.