Autorotations
I post this as I don't know
My current thinking is that as most helicopters can't select negative pitch an autorotation is dependant of main rotor velocity or rpm being held by the rotors inertia hence it is important to bottom the pitch ASAP to conserve momentum. But the guy in this video suggests something else, he states at certain angles of pitch part of the disk is windmilling as the helicopter descends and at the same time part of the disk is providing lift and an autorotation is a balancing act between the two to control your decent.
You need to go to 3 min into the video before he gets to the meat of the story.
Is that how it works?