Most photographers invest in filters to give them more flexibility in creating images. But there are so many types and some are expensive. There are UV filters, polarizers, neutral density filters, graduated neutral density filters that have a hard edge or soft edge,warming and cooling filters...... the list goes on. At times, I will use a polarizer or an ND filter, but as yet have not invested in the graduated ND filters. (maybe someday)
One reason I am not in a panic to do so is because of a great tool in Lightroom, the program I usually use to process my images. It has a graduated density filter tool that simulates what an actual filter would do. You then can manipulate the exposure, brightness, contrast etc. where you have applied the filter.
In the image below the sky and mountain was over exposed ( if i was more alert I probably could have avoided this in the first place ).
Fortunately, all I had to do is pull down the graduated filter in Lightroom to the desired area, make a few adjustments and I saved the image. Look below: