@ coyote:
I realize much of this is remedial, but I respond to you for the benefit of our OP.
In the helicopters I flew, letting Nr Run a bit too high in autorotative descent tended to increase Rate of Descent, a problem which will have to be dealt with in the flare and final pull/recovery. Then again, if you have a very tight landing zone, that may be a good tactic on a given autorotative descent. (Won't get into the esoterics of slips and unbalanced flight, no point at the moment).
This characteristic would make the generic mantra of "you can never have too much Nr" suspect, when you are trying to make the helicopter perform.
Controlling Nr and Airspeed isn't an academic exercise. It is intended to keep the speed and rate of descent manageable as you attempt to hit a safe landing spot, and also to keep your rotor system in the sweet spot so you have the most margin for error. Likewise, with a few extra turns, flight controls being linked to rotor performance, no point losing fore and aft, and lateral, control before necessary as the NR decays in the final input(s).
In support of SASless general comment, letting NR zoom/incr in the flare is generally OK, but only if doing so doesn't detract from your ability to brake the rate of descent in preparation of the final input that allows you to land safely (hopefullyl upright) on the ground/sea where you intended to.
In practice autos, overspeeding NR pisses off the maintenance folks due to added inspections, and I IIRC over time it can shorten component life. That irritates the boss who paid for the bird ...
In a real auto, where the engines or TR quit, there are larger fish to fry than yet another inspection cycle.
All said and done, I somewhat agree with your reservations on the NR comment, but we probably ought to spell out why, and in what flight regime.