I’ve been associated with two (I think THE two) Fan Blade Off events involving the BR 725 engines on Global Expresses. I personally knew the first crew. They reported a loud bang and instantly very severe vibrations that were disorienting, not in the spatial way, in a hard to read and understand the instruments way. They did nothing because couldn’t decide what to do. Soon the engine shut itself down. There was still vibration, but reduced. The USAF E-11 crew had a similar event, but despite using the old “move the throttle to identify the dead engine” decided wrong and caged the wrong one. The affected engine shut down and the vibration, we believe, continued. The crew appears to never recognized the engine with status message ENG SHUTDOWN was perfectly usable and could have restarted, perhaps due to extent of continuing vibration.
Doing nothing until you understand the situation you are in is very valid. If you can keep your guts out of your throat, of course.
BTW, the Gulfstreams with BR 725 have a very specific procedure due to the possibility of the FBO engine creating an harmonic with structure at certain speeds.