SmartSharpen is not intended to be a global, "Super Unsharp Mask" filter. It is meant to remove lens blur or Gaussian blur from specific areas of a photo, not the entire image.
The name is misleading. It is supposed to be called "smart" because you can control its effects in the shadows, highlights or midground of the image.
For global sharpening, it is best to use the good old "Unsharp Mask" filter.
The way I do it is to create a second, duplicate layer of the image (or part of an image) I want to sharpen and apply the USM filter to that. I apply just a hair bit more than I really want in the final product. Then I fade the layer's opacity to approximately 50% and experiment with layer blending modes until I get it to look the way I want.
My final settings usually end up being in the 30 to 50 percent range and I often find that setting the layer blending mode to "Luminosity" helps too.
Everybody has their own style and technique so the best thing to do is to experiment and see what you like best.