You should know when not to use the rule of thirds in photography. It's one of the first basic composition principles I teach to young photographers. As you advance in your skills, it's also wise to know that it's one of those rules of composition that should be broken at times.
In the photo below the horizon was placed at the one third level and the sailboat was placed at an intersection of the one thirds lines.
Not a bad photo, but not an award winning image either.
I am a member of one of the big on-line galleries, called 500pix. They recently gave me permission to use a bundle of their photos on the Digital Photography Tips web site. Some of the photographs followed common rules of composition and some did not.
For the beginning photographer, rules such as the rule of thirds, use of diagonals, negative space, and color theme are all useful to improve your photos. The photo below uses diagonals very effectively and a variation of the rule of thirds.
Rule of thirds used in pose of dancers
The fruit photo below does not use the rule of thirds, but is still a nice composition. The repetition of the roundness and the complimentary colors of all of the included object work well together.
The wooden chop sticks add the only diagonals in the composition but don't really compete with all of the fruit. Some viewers might argue that the grapefruit is the dominant object because of its size.
Composition with no dominant center of interest
In the photograph below, the photographer chose to place the end of the "tunnel of colored leaves" in the center of the photo. There is no right or wrong way to compose. The 2nd photo below that one is the same image, except cropped how I would have done it if I were the photographer.
Which one do you like better?
There are times when you should not use the rule of thirds to get the most interesting image. In the photo below the photographer intentionally made an almost perfectly symmetric composition.
I am not sure what message the photographer was trying to convey, if any, but it certainly is an interesting photograph, isn't it?
These photos were chosen so that you might play around with your own compositions. Knowing when not to use the rule of thirds is definitely subjective and should be explored on an individual basis.
Have a blast with your photograph!
Watch less TV
Shoot more photos.