Photoshop is like a big box of tools. Any number of features can get you where your headed but they won't work in every situation. The real trick to Photoshop is learning which tools do what and how.
When I shoot for myself I can control things like camera settings, composition of the subject, lighting etc. Especially the subject. I pick models with the right combination of features that I'm looking for: Great Skin, Even Tone, Striking Bone Structure. I have custom made action/filters to speed up my workflow when the variables are to my liking.
I don't get that luxury when I retouch for clients. I pretty much have to work with what I'm given. That's where understanding the PS tools, etc comes in handy. Then I can build the retouch workflow based on what works for the image and the expected outcome.
Attached is the stack for this retouch as asked for by a viewer.