Puntz,
The general idea of the concept is to cover as many place prices as feasible to make sure you that if you do not win you will at least get some of your stake money back. eg. 8/9 runners in a 10 field race or 6 runners in a 7 field race. Obviously it has holes as does other systems.

Like other systems, it becomes more effective if you apply form or are handy at handicapping.

What I did not mention in my original post is that I am using it with a broader betting system that I am currently trialing.