Years ago, when I was dressmaking, a client brought me a RTW skirt to alter and I was intrigued by the pockets. They were side seam pockets but I could not see how they had been sewn into the seam. It wasn't until I found the method in a Kwik Sew pattern that I realised the pockets were sewn entirely to the front of the skirt. In most pattern instructions, you sew one pocket piece to the front, one to the back, then you sew them together when you sew the side seam and this means you must clip the back pocket seam allowance in order to turn the pocket to the front of the skirt.
This never made me happy as I really dislike clipping seam allowances. You never see this done in clothes that you buy; why should we do it in our own sewn garments?
With this method, one pocket piece is placed, right side down on the side of the skirt and you sew three sides of a square at 3/4" from the edge, as indicated on the pattern piece in the photo.
Then you trim out the fabric and clip into the corners, then turn the pocket bag to the inside and press. It is advisable to interface the edge of the pocket to provide stability for this pocket method.
The other beauty of this pocket method is that it doesn't gape. Have you ever noticed how those other side seam pockets pooch open and you can only see it from the back? not pretty, in my opinion. These pockets lie flat because they are all connected to the front which eliminates any possibility of gaping.
Loes Hinse also uses this method on her Cruise Pants and she also top-stitches the edge of the pocket opening to reinforce it and keep it nice and flat, I suppose. But that is not really necessary.