I like to paint in photoshop too, but I do it differently than you do. How many layers do you use? I've also found if you use the airbrush, what you used for the hair shading, you can use it (just find the right size for your needs) for shading. Just lessen the opacity & pick a darker color for shading/lighter for highlighting, both work, & put down the color where you want it & you don't need to worry about blurring it. You can actually get some nice subtle shading that way & it'll save you a step.