Do you use Photoshop to undo the effect of a real ND grad?

For example, think about if you shot a photo with an ND grad, and the subject is sitting above the horizon, like a lighthouse. The ND effect would apply to both the sky and the lighthouse.

If you shot this photo without a filter, people would mask the lighthouse when applying a gradient filter, thus leaving the lighthouse untouched while editing the sky.

So what do people generally do when you use real ND grads, do you go back and try to undo the effect it has on the lighthouse? Or would you leave it alone?

I suspect most would do two photos - one for the foreground and one for the sky and then blend them in editing. ND grads are great, but as you point out when there isn't a clear line in the scene they become less suitable. Sometimes you can adjust two ND to suit a more complex scene; other times its just easier in the digital age to use tone-mapping and HDR methods to blend two frames together.

Masa Yume wrote in post #17434328
So what do people generally do when you use real ND grads, do you go back and try to undo the effect it has on the lighthouse? Or would you leave it alone?

I wouldn't ever use a real ND Grad for exactly the reason you described. It is very rare that a scene would ever have a flat dividing line between sky and ground. It is better to take multiple exposures and blend them in post.