We often use some software to help us to do the disc cleanning, such as the CCleaner, IObit Smart Defrag, for we thought the fragments will take too much space. While it is not the case. What fragments bring to the computer is more time needed when read and write fiels for hard disc. The damage to the disc is so less so being ignored. So there is no need for frequent disc defragmentations, it is not so important to do it everyday. Especially in Windows 8, it's performance has been improved a lot. That's not mean that no need, just no need for quite frequent use.