If I may, AdvancedSystemCare (even the free version) does a full scan of the computer, removing errors and optimizing the system.
It also comes with a Defragmenter program that may be useful.
I must warn against Driver Booster (which tends to install from the suite), and if you have Windows Updates set for "notify but let me choose," it will override you on scanning. But other than that, I've found it worked wonders on most of my systems.
Anyways, I tend to run the scan with AdvancedsystemCare, do a bit of file cleaning (removing duplicate documents or downloads, or uninstalling a program I realize I no longer use,) and then proceed to defragment.
In the save vain as hamlouis, I run the scans if I feel like it will benefit. And then proceed to defrag if the scans picked up a lot, or proceed to delete some stuff, and then defrag.
Edited by Legobot90, 02 December 2015 - 11:55 AM.