Lately, most of the people use large monitor as their desktop. If you have monitor size of 1680×1050 pixels then if you print screen the entire screen, the file size will be much larger than after adjusting.
If you clever enough, you will make use your photoshop and shrink the file dimension. Therefore, if you want to print five screens then you have to repeat that five times. That will be troublesome, I think.
The easiest way is by adjusting your screen resolution inside Display Preference Pane. Using QuickSilver search for
playpref and you will got application you want. Or you can go under System Preference.
However, when adjusting to smaller resolution, your display will looks awful. I suggest as soon as you finish your print screen, revert it back to initial condition.
The outcome will be like this.
Now, print your entire screen will no longer be troublesome. Enjoy it.