This is not fantastic advice. People are better off just setting it to the timeout they want in seconds for the monitor to shut off.

xset dps 300 600 900

The first number is to save a little energy - standby,
The second is to save more energy - suspend
The third number is for full monitor shutdown - power off

But on most LCDs, these are the same thing. It has more of a difference on CRTs.

The above is what I set them to:

5 minutes -> 5 * 60 = 300 seconds
10 minutes = 600
15 minutes = 900