NOT ALWAYS TRUE!!! But when it is true this is why...

Hi there - since nobody else has replied to you I guess I better.

Most people devise a system based upon a selection of races over a period of time. They tailor the system by making those "rules" you speak of.

They then make the mistake of adding new "rules" specially selected because they suit the selection of races they are looking at and return a great theoretical profit.

Anyone can make theoretical profits by designing rules in this way!!

You need to choose your rules, set them in concrete and then test them out over a future period to be sure it will work.

If you then return a profit you may be onto something

Best of luck...