I was chastised (politely, I might add) for not using GND filters recently. I know there are a few GND aficionados on IIS, so what I'm about to say might be seen as a bit controversial!
I would like to show you an example of why I don't see GND filters as the only way to achieve a pleasing landscape shot that includes a dramatic sky, yet retains detail below the horizon.
On my recent trip to the Great Ocean Rd, I was faced with overcast skies, yielding a flat light with low contrast. This produced the first attached image (straight out of camera).
Manipulation of white balance and exposure yielded the second image.
I than added a "graduated filter" in lightroom and made the third image. This replicates what you might have expected if you had used a GND filter in front of the lens. Note that the apostles are quite dull.
I then "painted in some light" (using the Adjustment Brush) onto the apostles and produced the fourth image.
I believe this ultimate effect would have been impossible to achieve "in camera", unless you had a custom GND filter that had the appropriate "cutout" to permit light through for the apostles.
The histogram of the first image is entirely within the range of the histogram (no clipping of whites or blacks). I haven't tried to drag any detail out of the shadows or highlights. I've selectively lightened and darkened the image, just like a skilled darkroom worker would have done with dodging & burning under an enlarger (I've seen an expert doing this, and it was amazing to watch). I had the impression that photographers who manipulated images in the darkroom were held in high esteem - the first "post processors". Now that we have these tools easily available to us through software like Lightroom, some people seem pre-occupied about getting everything right "in camera".
Just my two cents worth!
DT