First Landscapes Using Filters
If I may:
1: The lower part of the picture needs at least the same amount of grey filtering as the bright clouds in the sky. Blown out specular lights are OK, but this is too much, for my taste anyway. I alo find the brown fltering for the lower part to be too obvious.
2: Here, your filtering is a success, maybe a bit too much. The clouds could be a bit brighter.
3: Same a 2. Lovely landscape. I personnaly would have tried to keep the clouds a bit brighter.
4: Tough case, but I think the filtering goes too low, making the mountains too dark. It also makes the foreground unnaturally bright. In such a case, I expose for the highlights, letting the shadows fall where they may, hoping to be able to salvage them by some light filling in post. Spot metering the different areas of the scene can give you the brightness range you are facing and can help you decide if it is worth it to try or not.
5: Same problem as 1, only much worse. This scene might have needed no filtering at all ot maybe for the lower part instead of the upper part. The water is completely over-exposed and I don't find the result to be pleasing.
Graduated filters are not easy to use. I have done much worse with them!