If you want nice crisp corners try using the wrapped corner technique. Instead of pivoting at the corner stitch the seam to the end. Now take it to the ironing board and press the seam at the stitching line folding the seam allowance towards the center. This wraps the seam allowance. Start the connecting seam at the folded edge. After completing the seams trim the corner at and angle to reduce the bulk. Turn the corner right side out and press for a very neat corner. step 1step 2 and 3step 4finished corner
You can refine this more and eliminate more bulk by grading the seam allowance click here and then understiching the entire seam. click here Fold along the seam line with right sides together and the seam allowance will be wrapped. Stitch the connecting seam click here turn, and press.click here
compare the difference in bulk in the seam allowance click here
I use the technique on collars, pockets, and any corner I want to be very crisp.
I learned the technique from Sewing with Nancy and she has the details in several of her books