I agree with Old Akro and Tinstaafl regarding confirmation. Even by using the throttle on a piston twin to confirm I also teach to check fuel flows and EGT.
There is another very good reason for closing the throttle on a piston twin and probably other types as well. Unless you are terrain critical you will be doing some trouble shooting. Having an engine come back to life with a cruise throttle setting is most likely going to result in a rather large engine/prop overspeed which will mean expensive teardowns for the engine and prop. There will be a significant yaw as well.