When I work on images in Photoshop, I normally do a number of adjustments (spot healing, dodge/burn, curves, etc) before I mess around with blending modes. I then merge visible to a new layer and apply Soft Light. I don't really like to do this though because I might then stack additional adjustment layers on top of this blended layer. If for any reason I need to change the layers beneath this new layer, the Soft Light layer won't reflect the change. Is there a way to apply blending modes without duplicating layers?
When you finish editing the picture, select all layers and convert them to a smart object instead of merging the layers. Then duplicate your smart layer to apply the blending mode you want.
It would be a litte more flexible if you just added a blank levels or curves layer and set the blending mode of that layer to Soft Light. Or an action that does a merge visible + curves adjustment layer w/blend mode soft light.
The adjustment layers will take very little space compared to duplicating the layer.