I suppose if one gets right down to brass tacks....it is how one. has been taught in the past that sets you up for success or failure.
Helicopter Pilots live and die by Nr.....too much Nr is usually an inconvenience with a rare occasion that it might be serious.....too little Nr can almost certainly lead to dire consequences especially in a single engine machine....not so much on a Twin.
The crucial teaching point is checking the Nr BEFORE moving the Collective Lever.
You move the Lever then check Nr and what you see is not going to be indicative of the problem you are experiencing necessarily.
Said PM could. have used a more descriptive announcement such as identifying whether the Nr was high or low.....and the PF would have had a clue as to what he should be seeing on the Rotor Tach before. he moved the Collective.
There is more to converting to a Twin Engine Helicopter than meets the eye....and add in a Second Pilot to the Mix and you have additional issues to work around.
The final observation I would make is not all malfunctions appear in the Check List or always have the exact symptoms discussed in training.
That is why I taught the importance of thinking first.....and acting second....to the point with some of the Dropped Shoulder Crowd I insisted they punch the Clock before doing anything at all.
It does not achieve any progress on resolving a problem but it darn tooting affords those who want to leap into action and do something.....as punching the clock does absolutely no harm.....but moving the wrong lever or throwing the wrong switch can surely ruin your day.