In case you didn’t know this, try it next time you use a built in or custom shape in Photoshop. Select the shape tool, then look up at the top bar – that’s where Photoshop displays the tool options. As long as you’re using the SHAPE and not PATHS or PIXELS option, your path can be customized. You can modify paths but it’s more difficult to see what you’re doing.
As long as you’re on a shape path layer you can go to the EDIT menu and you’ll see TRANSFORM PATH and FREE TRANSFORM PATH, you can use these tools to scale, flip, bend, fold, spindle and mutilate your shape. For more control, you can choose the DIRECT SELECTION tool from the toolbar (which is the white arrow) so you can manipulate separate points, or the PEN tool where you can add, delete, or transform points.
Photoshop doesn’t have the best vector creation tools, but that’s what Illustrator is for! But being able to quickly modify a shape in Photoshop is definitely useful.