Let's say you want to stack a contrast, a saturation, and a color temp adjustment layer (or levels/curves/or a color threshold/etc.), then want to keep tweaking

Let's say you want to stack a contrast, a saturation, and a color temp adjustment layer (or levels/curves/or a color threshold/etc.), then want to keep tweaking them until you're happy. I do this often. Or you have them right but just want to change the mask a bit to add/subtract a bit you missed. Or change the image under those adjustments. It's trivial with adjustment layers and done in a few steps trivially. It's not if you're copying layers and tweaking away and backtracking and reverting in separate layers.