C172. Engine fire in flight procedure

[double_barrel]

The POH and my instructor say:

1. Mixture to idle cutoff
2. Fuel selector to OFF

But I read somewhere that leaving the engine running could potentially burn off fuel in the system that would otherwise add to the fire, so if the engine is running better to turn off the fuel but leave the mixture alone. That makes a lot of sense to me.

Any thoughts? If I was able to defend this procedure to an examiner, would it be acceptable?


Thanks