Extremely important to keep RRPM in the green above anything and everything else. The airspeed doesnt mean anything if the blades stall, the altitude doesnt mean anything (except a further fall) if the blades stall. If you keep the RRPM in the green and have zero airspeed and end up right in the middle of the HV curve you are still better off, atleast then you have control over the aircraft and even though you may be dropping like a rock and have no way to flare at the end, you still are falling slower than if your blades had stalled and in that case you still wouldnt be able to flare.
I think the routine training of 75 knots, 500' AGL auto entries is what gets us into this horrible habit. When we train we never want to trade off airspeed for RRPM because it is never really that low (not a big surprise to get a simulated failure in training) and if we do give up our airspeed we have to get it back and it makes more work. I found myself fall into the trap when at about 300 hours instruction I had a student lower the collective about halfway and roll the throttle off when we got a traffic alert during instrument training. I was bent over looking for the traffic, a little complacent, and a lot confused to be hearing the horn on an instrument flight. I lowered the collective still trying to figure out what happened and looked at the RRPM which was at about 88 percent. I just keep the collective full down and waited for the RRPM to build. It wasnt until the RRPM was at about 95 percent that I realized I could just pull back on the cyclic more and get the RRPM into the green and start looking for that traffic again. I had plenty of altitude, all ended well, but its now always on my mind to use that airspeed when you need it above all else.
As a side note, as an instructor in the R22 my hand is always on the collective on take offs and landings, no matter the student level.