I love layer styles; they can add so much with so little effort. They’re much faster than having to create these effects with channels and filters. There are times when you want to convert these styles to individual layers; a prime example is when you need a cast shadow. While a drop shadow makes it look like an object is floating in front of a flat background, a cast shadow will anchor it to the scene.
When you cut out a person and drop them into a different background, you need that cast shadow to make it believable. Usually, you have to warp the shadow, or skew it and add a fade to get realism. You can’t do that with a Drop Shadow. You can, however, use that drop shadow if you turn it into a regular layer.
In the Layers panel, Right-click on the layer style on your layer (after you’ve made the Drop Shadow) and choose Create Layers. This will separate out all your layer styles and put them on regular layers. Now you can manipulate them as much as you want to create your cast shadow. Create Layers works for all layer styles, including Strokes and Bevels, not just Drop Shadows.