Chucklehead - most aircraft have the ability to beep up the Nr for critical stages of flight, either manually or automatically and it would be specified in the RFM (well it is in mine) for PC1 profiles.
As you say, the point is that you start from a higher Nr figure which gives you more time to react to an engine failure. If you have a low Nr horn on your aircraft, that is what to pull to followinfg an engine failure, then lower the lever until the horn ceases again, that should give you optimum Nr and max single engine power.
It is worth noting that the helipad departure (up and back) often has a limited rate of climb specified in the RFM which is to keep the pitch angles lower in order to avoid rapid Nr decay following and engine failure; this is somewhat at odds with the military view where you get to height quickly to reduce exposure time to the reject option.