You do not lose any points because the center of your sewn square becomes the corners of your 4 resulting HST. You just have to ensure you start with the correct size squares.
The technique is to take two squares, a light and dark, placed right sides together and sew 1/4 around the peremiter them cut diagonally both ways (cutting an "X" through the square). This results in four HST. The main disadvantage to this technique is you end up with all your edges being cut on the bias. Personally, I would never assemble HST in this manner, there are too many other shortcut techniques that produce HST where your straight edges are not on the bias.