(This is today's bit of advice from the book Safety Toolbox.)
Dead zones are dangerous places to leave the object balls for your opponent to shoot. These are named "dead zones" because there are limited places on the table where you can put the cue ball so the object ball can be pocketed.
Object balls in the center of the table provide many target pockets. Object balls in dead zones usually only have one possible target pocket.
The shaded areas in this graphic show the table areas known as dead zones.
When an object ball is positioned within these areas, it is tougher to play. There are only two pockets the ball can be shot into. Plus, the cue ball must be positioned within a very small table area in order to have an angle on that ball.
It's not easy to get the cue ball into position to be able to shoot an object ball in a dead zone. The player either has to shoot a bank (with a lower success rate) or play a defensive shot.
When you have to shoot a ball in a dead zone, use Bank into a safety (see page 103) as your standard response. This approach reduces the wear and tear of attempting to make an offensive effort.
With careful planning, use these dead zones to make things difficult for your opponent. You can be pro-active and create dead zone problems by using combinations and caroms. If several balls are in dead zones, you can have some confidence that a run out is difficult, if not impossible.
To really frustrate an opponent, put two balls that he must shoot into the short rail dead zones at opposite ends of the table. This requires that he send the cue ball a long distance to get position from one to the other. If he is the least bit careless, he can't make the second ball.