I haven't read all replies, so don't know if anyone mentioned this yet...but:
The quality of the roads you have to practice on can make a difference. My biggest local descent is down a mountain, and the road often has gravel patches, and there are large areas of pavement patches. There also tend to be a lot of tourists looking at the view more than the road.
Earlier this summer I went to to a ride with wonderful descents. Barely any traffic. Smooth pavement. Zero gravel. It was so much easier to really feel and flow with the curves...to integrate what I know I'm supposed to do on descents with what I'm feeling on the descents.
I felt some skills sort of click in that I had been trying to practice at home, but was not really able to truly focus on and get into my body, if that makes sense.
"The best rides are the ones where you bite off much more than you can chew, and live through it." ~ Doug Bradbury