Yep. Shadows have little or no detail from the get go if the highlights are properly exposed.
It's the opposite of blown out highlights, and is called blocked shadows.
Blown out high;lights are R = 255, G = 255, B = 255 and no detail can be recovered. Blocked shadows are R = 0, G = 0, B = 0, and there are no details that can be recovered.
Fully 1/2 of the luminosity data in a digital image is in the brightest stop of exposure.
The next darker stop (2nd stop) then has 1/2 of what's left, or only 1/4 of the luminosity data.
The next darker stop (3nd stop) then has 1/2 of what's left, or only 1/8 of the luminosity data.
The next darker stop (4nd stop) then has 1/2 of what's left, or only 1/32 of the luminosity data.
The next darker stop (5nd stop) then has 1/2 of what's left, or only 1/64 of the luminosity data.
The next darker stop (6nd stop) then has 1/2 of what's left, or only 1/128 of the luminosity data.
And so on.
Understanding Dynamic Range in Digital Photography
If your camera has a 12-bit A/D converter, the dynamic range of Raw files from your camera should be about 12 stops.
If your camera has a 14-bit A/D converter, the dynamic range of Raw files from your camera should be about 14 stops.
Though JPEG is a lossy file type. It keeps all the luminosity data because all the luminosity data is needed to make an image from a Raw file.
All the color data in a Raw file is not needed to make a JPEG, which is why JPEG discards about 80% of the color data.
You can see an approximation of your cameras image sensor's dynamic range by looking at the image histogram of the Raw file as it is displayed in Lightroom or Camera Raw.
The histogram displayed on the back LCD of a digital camera is not the histogram of the Raw file. It is the histogram of a JPEG Basic thumbnail that is embedded in the Raw file.