An LSD will help with traction in a straight line. An open diff will always transfer the the same power to both wheel. When one wheel starts to spin, and it does not take much power to make it contiune spinning, the other wheel will get the same amount of power. This is why it's called a "complete loss of drive" when one wheel slips. The other wheel will get the power it takes to keep the wheel spinning. Imagine one wheel on ice, and the other on tarmac.. An LSD will be able to transfer the power to the other wheel and give drive.

So if you se one skid mark in your rear wheel mirror, you know you have not utilised the engine's full power.