That's something that I personally always found tedious with 16-point Garbage Matte, but now it's much quicker to free-form outline a figure.

If you need more detail, the mask Pen tool will allow you to create more complex multi-point masks, such as to garbage matte out someone in front of a green screen.

You can still create very quick masks using the built-in Opacity masks simply click the rectangular or oval mask buttons and you have a 4-point mask applied to your clip, which you can adjust easily to accommodate the shape you need.