Since the histogram is computed from JPEG that is burned into RAW file using Picture Control (PC), how can one actualy rely on it? How precise is it when PC is set to Neutral?
Simple test: Make 2 RAW pictures of colorful bonbons using Manual mode, one with Neutral PC and the second one with Vivid PC. Check the RGB histogram and you'll see the difference. But when you import the image into Lightroom, it manages RAW file it's own way and there is no clipping. Both images looks same.
I always shoot Neutral, but I am not sure if I can trust the histogram since this "discovery"..