Meanwhile, in Lightroom with a graduated filter, if in an extreme you need three stops of extra light for the dark area of the picture, your 100 ISO for the picture is ramped up in post processing to 800 ISO (3 stops - 100 - 200 - 400 - 800) and who wants a picture at 800 ISO on a sunny day?
By using a bracketed set, you can adjust your shutter speed and get multiple exposures at 100 ISO (if conditions allow) and blend them for a more pleasing image with the gradient exactly where you want it to be.
i) open both pictures in Photoshop
ii) on one picture, select all and then copy and paste to the other picture to create a new layer
iii) select both layers and select edit/auto align layers so that the layers perfectly fit
iv) add a layer mask to the new layer
v) with the layer mask selected use shortcut key 'G' to select gradient and then do a black to white gradient that hides/reveals the light/dark areas as required.
this can be seen below on a screengrab from the Photoshop edit.
combine layers and save as a JPEG for your final image. After you do this a few times, you will find it takes just seconds for the whole process. There are always many ways to do the same thing with digital photography, and this just provides another tool in your toolbox, but definitely worth knowing for when light and shadow is pushed to the extreme,