The pyramid rule is something I have always found useful for explaining to young and intermediate players why it is important to develop a 'close to the table' game. The concept revolves around the increasing distance between two wide angle balls the further back you go from the table.
The best way to show a young player is to feed 2 balls, one to each corner consecutively. Close to the table (A) they can move and hit both balls in turn. You then ask them to move back 1-1.5 metres from the table (B). They get the first ball but have to stretch or play out of balance for the second ball. You ask them to move back again to around 2-2.5 metres from the table (C). It becomes very difficult for them to get to the ball.
The diagram above shows the point illustrated. So why is playing close to the table important?
To build this close to the table game you need to be fearless, when the opponent attacks you need to hold your ground and be confident. Timing is very important and placement. When you get the chance to attack, being close to the table can make your shots far more devastating in terms of opponent reaction time than if you are far back playing a slower opening game and loop to loop counter style. At the table you can use an early bounce counter style which can be very effective.
So remember the pyramid rule when you find yourself drifting back from the table and remember you are much better off staying up at the table!